The present invention relates to new enzymatic compositions and the uses thereof to hydrolyze hemicellulose. More specifically, the invention relates to improved enzymatic compositions containing a new polypeptide having arabinofuranosidase and β-xylosidase activity, and the uses thereof for modifying a hemicellulose-containing biomass. The invention further relates to methods for producing fermentable sugars from biomass using such enzymatic compositions.

Background of the invention

Cellulose and hemicellulose are the first and second most abundant polysaccharides in nature. Cellulose represents from 30 to 60% and hemicellulose represents about 20-40% of lignocel lulosic biomass such as in corn fiber, corn stover, wheat straw, rice straw, and sugarcane bagasse. Hemicelluloses are heterogeneous polymers of pentoses (xylose, arabinose ), hexoses ( mannose. glucose, galactose ), and acid sugars. For instance, hardwood hemicelluloses contain mostly xylans, whereas softwood hemicelluloses contain mostly glucomannans.

Biomass wastes and byproducts containing hemicellulose are generated by numerous manufacturing processes, and food and agricultural processing. A common example of such biomass material is the waste and byproducts from grain processing such as the stalks and leaves of the grain plant. For instance, wheat bran is a large volume biomass material that includes up to 40% weight hemicellulose. Disposal of such biomass material is becoming an increasing problem and the conversion of biomass material to higher value materials has considerable interest.

Additional ly, fermentable sugars are increasingly used to produce alcohol (e.g., ethanol ) as an alternative to liquid fuels, plastics, polymers and other bio- based materials such as lactic acid. The demand for abundant low cost fermentable sugars, which can be used in l ieu of petroleum- based fuel feedstock, is growing rapidly. Typically, the enzymatic conversion of hemicellulose to fermentable sugars, e.g., glucose, xylose, arabi nose, galactose, mannose, and/or other hexose (C6) and pentose (C5) sugars, leads to a useful and abundant renewable source of raw material for a variety of useful chemicals and biochemicals.

Three major approaches have been developed to convert hemicellulosic biomass (i.e. biomass containing a high content of hemicellulose. such as at least 10% by weight of hemicellulose ) into fermentable sugars. First is chemical hydrolysis, wherein hemicellulose is generally separated in the first step from the lignocellulose composite material by the action of an acid or alkali. In a second step a higher temperature acid hydrolysis process hydrolyzes the plant material cellulose. Despite its efficiency to produce C6 sugars, the acid process also produces other by-products that interfere ith the use of the sugars in downstream processes like fermentation to useful products l ike lactic acid, alcohols, organic acids etc. Furthermore, in order to reduce effluent and pollution problems it is required to recover or neutralize the acids at the end of the process.

The second approach is thermal hydrolysis. Said thermal processes, such as Steam Explosion processes, are cleaner since they do not make use of any chemicals. However, these processes lead to low sugar yields, formation of unwanted by-products that may inhibit downstream processes, and are energy intensive.

The third approach consists on enzymatic hydrolysis, optionally preceded by pretreatment. steps. Enzymatic processes use enzymatic compositions for hydrolyzing hemicellulose. These processes are much cleaner and low energy consumers for hemicellulose hydrolysis and finally provide better quality fermentable sugars in higher yields. However, the hydrolytic efficiency of an enzymatic composition can depend on a multitude of factors, e.g., hydrolytic properties of individual enzymes, the synergies among them, their ratio in the mixture, etc. The hydrolytic efficiency of enzymatic compositions is one of the major factors that restrict these enzymatic processes.

Despite substantial progress and huge interest in the field, there is still a need in the art to identify enzymes and enzymatic mixtures or blends that are suitable for converting hemicellulose contained in a biomass into fermentable sugars ith sufficient or improved efficacy, improved fermentable sugar yields, and/or improved capacity to act on a greater variety of biomasses containing hemicellulose.

Summary of the invention

The present invention provides novel compositions having improved hemicellulolytic activity and the uses thereof to transform hemicellulose-containing biomass. In particular, the inventors have identified an enzyme of the Glycoside Hydrolase family 3 (GH3) which exhibits remarkable dual arabinofuranosidase and β-xylosidase activity. The inventors have further shown that this enzyme may be efficiently used in an enzymatic mixture or blend, such as in combination with a xylanase, to optimize hydrolysis of hemicellulose, particularly arabinoxylan contained in hemicellulose.

It is therefore an object of the present invention to provide a composition comprising at least (i) a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2, and (ii) a xylanase.

Advantageously, the composition further comprises at least one polypeptide selected from the group consisting of a β-xylosidase, an arabinanase, a glucanase or an esterase.

The invention further relates to the use of such composition for modifying a hemicellulose- containing biomass. The invention also relates to the use of a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID NO: 2, or of a microorganism expressing said polypeptide, for modifying a hemicellulose-containing biomass, and optionally producing fermentable sugars from the hemicellulose-containing biomass, more preferably xylose and arabinose.

It is another object of the invention to provide a method for modifying a hemicellulose- containing biomass, comprising:

a) contacting such a biomass with a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID NO: 2, or with a microorganism expressing said polypeptide;

b) optionally recovering fermentable sugars from the modified biomass of step a), and c) optionally fermenting the fermentable sugars of step a) or b).

In a particular embodiment, the biomass is contacted in step a) with at least one further polypeptide selected from the group consisting of a xylanase, a β-xylosidase, an arabinanase, a glucanase, and/or an esterase.

It is a further object of the invention to provide a method for modifying a hemicellulose- containing biomass, comprising contacting the biomass with a composition as defined above. The invention also discloses a host cell, such as a lactic acid bacterium, comprising at least a nucleotide sequence encoding a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2.

The invention further relates to a kit for hydrolyzing hemicellulose, comprising at least

- a polypeptide having at least 55%, 60%, 65%,70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2; and

- a xylanase, preferably a xylanase of Glycoside Hydrolase family 11 (GH11) or 10 (GH10), with preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°4 or 6 respectively.

Legend to the figures

Figure 1 shows the enzymatic hydrolysis of wheat bran using different enzymatic cocktails. Assays were performed at 2% substrate concentration, pH6, 30 °C and for 24h. Reducing sugars (xylose equivalents) were determined by DNS method;

Figure 2 shows a comparison of the effects of an enzymatic cocktail of the invention comprising arabinofuranosidase Abf_3 and a xylanase, with an enzymatic cocktail comprising an arabinofuranosidase of the prior art (Abf_51), a β-xylosidase and a xylanase on the enzymatic hydrolysis of wheat bran. Enzymatic hydrolysis assays were performed using 2% wheat bran at pH6, 30 °C during 24h. Reducing sugars (xylose equivalents) were determined by DNS method;

Figure 3 shows the positive effects of additional enzymatic activities included in the enzymatic cocktail of the invention, on the enzymatic hydrolysis of wheat bran. Assays were performed at 2% substrate concentration, pH6, 30 °C during 24h. Reducing sugars (xylose equivalents) were determined by DNS method;

Figure 4 shows a comparison of the effects of an arabinofuranosidase of the prior art (Abf_51) to the effects of the arabinofuranosidase of the invention (Abf_3) on the enzymatic hydrolysis of wheat bran. Assays were performed at 2% substrate concentration, pH6, 30 °C during 24h. Reducing sugars (xylose equivalents) were determined by DNS method;

Figure 5 shows a comparison of the effects of different enzymatic compositions commercially available to the effects of an enzymatic composition of the invention on the enzymatic hydrolysis of wheat bran. Assays were performed at 2% substrate concentration, pH6, 30 °C during 24h. Reducing sugars (xylose equivalents) were determined by DNS method;

Figure 6 shows the effect of a cellulase supplementation in different enzymatic compositions on the enzymatic hydrolysis of wheat bran. Assays were performed at 2% substrate concentration, pH6, 30 °C during 24h. Reducing sugars were determined by DNS method; Figure 7 shows a comparison of the effects of an enzymatic composition of the invention to the effects of a control composition on the enzymatic hydrolysis of pretreated wheat bran. Wheat bran was submitted to a physicochemical treatment. Assays were performed at 2% substrate concentration, pH6, 30 °C during 24h. Reducing sugars (xylose equivalents) were determined by DNS method;

Figure 8 shows the enzymatic hydrolysis of wheat bran using different enzymatic mixture; Assays were performed at 2% substrate concentration, pH6, 30 °C during 24h. Reducing sugars (xylose equivalents) were determined by DNS method. Detailed description of the invention

The following is a description of the present invention, including preferred embodiments thereof given in general terms. The present invention is further exemplified in the disclosure given under the heading "Examples" herein below, which provides experimental data supporting the invention and means of performing the invention.

Definitions

The present disclosure will be best understood by reference to the following definitions. In the context of the invention, the terms "composition", "blend" and "mixture" are used interchangeably and encompass all kind of compositions comprising polypeptide(s) having an enzymatic activity. For instance, the mixture may comprise polypeptides and/or host cells encoding polypeptide(s) of interest or extract thereof, and optionally excipients and/or fermenting microorganism(s). The mixture may further comprise a biomass, optionally at least partially hydrolyzed. In a composition of the invention, the various constituents are typically in admixture. They may be in solid or liquid state, such as a solution, suspension, paste, gel, lyophilisate or frozen preparation. The term "biomass", in the context of the invention, designates any hemicellulose-containing materials, particularly any hemicellulose-containing vegetal material. Typically, biomass designates any plant biomass, particularly any unprocessed or processed material of vegetal origin. Examples of biomass include, without limitation, plant material, forestry products, including mature trees unsuitable for lumber or paper production, agricultural products, such as grasses, crops and animal manure, and aquatic products, such as algae and seaweed. Plant material and agricultural products include, but are not limited to, Miscanthus, energy grass, elephant grass, switchgrass, cord grass, rye grass, rye bran, reed canary grass, common reed, wheat straw, wheat bran, barley, barley straw, barley bran, canola straw, oats, oat straw, oat bran, corn stover, soybean stover, oat hulls, oat spelt, sorghum, rice hulls, rice bran, sugarcane bagasse, pressed sugarcane stalk, corn fiber, flax, wheat, linseed, citrus pulp, cottonseed, groundnut, rapeseed, sunflower, peas, lupines, palm kernel, coconut, konjac, locust bean gum, gum guar, soy beans, Distillers Dried Grains with Solubles (DDGS), wet or dried distillers grain, Blue Stem, corncobs, energy cane, cassava peels, cocoa pods, spent grain, vinasse, wood pulp fiber, sawdust, sugar beet pulp, locust bean pulp or other vegetable or fruit pomaces, pine, conifer softwood, eucalyptus, birchwood, willow, aspen, poplar wood, hybrid poplar, hardwood, softwood, short-rotation woody crop, crop residue, yard waste, or any combination thereof (see for instance Sun et al., Bioresource Technology 83 (2002) 1-11). Generally speaking, a hemicellulose-containing material or biomass contains at least one polysaccharide selected from xylan and heteroxylan, such as glucuronoxylan, arabinoxylan, glucomannan or xyloglucan. Preferred biomasses contain at least 10 % by weight hemicellulose, more preferably at least 20 % by weight. Advantageously, the biomass contains at least 30% by weight of xylan and/or heteroxylan.

Preferred is a biomass obtained from cereal grain, e.g. such as milled grain or byproducts from processing of cereal grain. Preferred cereal grain is a cereal grain selected from the group consisting of corn (maize), wheat, barley, oat, rice, sorghum and millet.

"Modifying" a biomass, or biomass feedstock, within the context of the present invention includes any modification thereof, including transformation, degradation, hydrolysis, conversion or processing of a biomass. The term "modifying" a biomass typically encompasses any modification of the biomass that results in the production of fermentable sugars, monomeric sugars, metabolites, biofuels, feeds, foods and/or chemicals, or any other useful product. Modification also typically encompasses the hydrolysis or modification of biological polymers of the biomass, such as hemicellulose. The term fermentable sugars" designates, without limitation, carbohydrates having a basic composition (CH ₂ 0)n. Based on the number of carbons (e.g., 3, 4, 5, or 6), the monosaccharide is a triose, (i.e., glyceraldehyde), tetrose, pentose (i.e., xylose), hexose (i.e., glucose), etc.

Herein, the terms "peptide", "polypeptide" and "protein" are employed interchangeably and refer to a chain of amino acids linked by peptide bonds, regardless of the number of amino acids forming said chain. The amino acids are herein represented by their one-letter or three-letter code according to the following nomenclature: A: alanine (Ala); C: cysteine (Cys); D: aspartic acid (Asp); E: glutamic acid (Glu); F: phenylalanine (Phe); G: glycine (Gly); H: histidine (His); I: isoleucine (lie); K: lysine (Lys); L: leucine (Leu); M: methionine (Met); N: asparagine (Asn); P: proline (Pro); Q: glutamine (Gin); R: arginine (Arg); S: serine (Ser); T: threonine (Thr); V: valine (Val); W: tryptophan (Trp ) and Y: tyrosine (Tyr). As used herein, "enzyme" designates a polypeptide having catalytic or enzymatic activity.

As used herein, the term "sequence identity" or "identity" refers to the number (%) of matches (identical amino acid residues) in positions from an alignment of two polypeptide sequences. The sequence identity is determined by comparing the sequences when aligned so as to maximize overlap and identity while minimizing sequence gaps. In particular, sequence identity may be determined using any of a number of mathematical global or local alignment algorithms, depending on the length of the two sequences. Sequences of similar lengths are preferably aligned using a global alignment algorithms (e.g. Needleman and Wunsch algorithm; Needleman and Wunsch, 1970) which aligns the sequences optimally over the entire length, while sequences of substantially different lengths are preferably aligned using a local alignment algorithm (e.g. Smith and Waterman algorithm (Smith and Waterman, 1981) or Altschul algorithm (Altschul et al., 1997; Altschul et al., 2005)). Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software available on internet web sites such as http://blast.ncbi.nlm.nih.gov/ or http://www.ebi.ac.uk/Tools/emboss/). Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. For purposes herein, % amino acid sequence identity values refers to values generated using the pair wise sequence alignment program EMBOSS Needle that creates an optimal global alignment of two sequences using the Needleman-Wunsch algorithm, wherein all search parameters are set to default values, i.e. Scoring matrix = BLOSUM62, Gap open = 10, Gap extend = 0.5, End gap penalty = false, End gap open = 10 and End gap extend = 0.5. The term "expression" , as used herein, refers to any step involved in the production of a polypeptide including, but being not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion.

Enzymes and compositions

The present invention is based in part on the discovery of certain novel enzymes having hemicellulolytic activities and, more particularly, of a new polypeptide exhibiting both arabinofuranosidase and β-xylosidase activity. The invention is also based on the design of novel compositions comprising particular blends or weight ratios of polypeptides having hemicel lulolytic activities, allowing efficient hydrolysis of hemicellulosic materials. In the context of the invention, hemicellulolytic activities include, without limitation, arabinofuranosidase, xylanase, xylosidase, glucanase, pectinase such as arabinanase, and esterase activities.

In a first aspect, the invention thus relates to a polypeptide exhibiting both an arabinofuranosidase activity and a β-xylosidase activity and having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2.

The invention further relates to a composition comprising (i) a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2, herein after polypeptide Pax, and (ii) a xylanase.

According to the invention, the polypeptide Pax exhibits both an arabinofuranosidase activity and a β-xylosidase activity. Accordingly, the polypeptide Pax allows an efficient hydrolysis of arabinoxylan contained into hemicellulose containing biomass. It is important to note that the hydrolysis of arabinoxylan is a major prerequisite for improved hydrolysis of cereal hemicellulose. Indeed, arabinoxylan is part of the water soluble and insoluble fiber present in cereals, in particular in the cel l walls. The use of the polypeptide Pax in a hemicellulolytic composition favors the degradation of cereal hydrolysis such as bran, wheat, etc. The inventors have discovered that the newly identified polypeptide of SEQ ID N°2, herein after Abf_3, belongs to the Glycoside Hydrolase family 3 ("GH3"). The Glycoside Hydrolase family 3 typically comprises broad substrate specificity. They remove single glycosyl residues from the non-reducing ends of their substrates. Catalysis occurs via a classical Koshland double-displacement mechanism with the anome ic configuration of the released glycose being retained. GH3 can be multi modular proteins with a catalytic module a diversity of 3D- structures. The first GH3 structure described is composed of two domain (α/β)8 barrel and (α/β) ₆ sandwich ( Varghese et al, Structure, 1999 Feb 15;7(2): 179-90). GH3 enzymes may be found in every kingdom, including eukaryote, prokaryote, microbial, fungal and algae. For instance, the newly discovered enzyme of SEQ ID N°2 has been extracted from the Microbial community of insect's digestive tract.

As used herein, "Glycoside hydrolase" (GH), and "Carbohydrate Esterase" (CE) refer to two classes of carboh yd rate- act i ve enzymes distinguishable by the type of reaction catalyzed as defined by the CAZy database (Coutinho. P.M. & Henri ssat, B. (1999) CAZy - Carbohydrate- Active Enzymes server at URL: http://afmb.cnrs-mrs.fr/~cazy/CAZY/index .html or alternatively Coutinho. P.M. & Henrissat. B. 1999; The modular structure of cellulases and other carboh ydrate-acti ve enzymes: an integrated database approach, in "Genetics, Biochemistry and Ecology of Cellulose Degradation"., K. Ohmiya, K. Hayashi, K. Sakka, Y. Kobayashi, S. Karita and T. Kimura eds., Uni Publ ishers Co., Tokyo, pp. 15-23, and Bourne, Y. & Henrissat, B. 2001 ; Glycoside hydrolases and gl y co s y 11 ra n s f e ra se s : famil ies and functional modules. Current Opinion in Structural Biology 11 :593-600). More precisely, GH's are a group of enzymes that hydrolyze the glycosidic bond between two carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. The CAZy classification system has grouped Gi ls according to sequence similarity into about 1 33 different famil ies.

According to the invention, the composition further comprises at least a xylanase. The combined use of the polypeptide Pax and a xylanase ensures breaking down hemicellulose.

In a particular embodiment, the composition comprises a xylanase, preferably a xylanase belonging to the Glycoside Hydrolase family 1 1 (GH 1 1 ). Advantageously, the xylanase of has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°4 (herein after Xyn_l 1 or NpXy ). Glycoside hydrolase family 1 1 ("GH11") enzymes have a β- jelly roll structure. They hydrolyze internal glycosidic bonds found in xylose-based polymers and are thus known as endo-acting enzymes that operate via a retaining mechanism that uses double displacement reaction with a glutamate residue acting as nucleophile and a glutamate residue being identified as acid/base residue. .Several other residues spread throughout the +1 and -2 subsites may contribute to stabilizing the xylose units in the substrate neighboring the pair of xylose monomers that are cleaved by hydrolysis. GH 1 1 enzymes may be found in every kingdom, including eukaryote, prokaryote, microbial, fungal and algae. In particular embodiments, the GH 1 1 xylanase is extracted from the Microbial community of insect's digestive tract.

Alternatively, or in addition, the composition comprises a xylanase belonging to the Glycoside Hydrolase family 10 (GH10). Advantageously, the xylanase has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°6 (herein after Xyn_10).

Glycoside hydrolase family 10 ("GH10") enzymes have an (a / β ΐκ-barrel structure. They hydrolyze internal glycosidic bonds found in carbohydrate polymers and are thus known as endo-acting enzymes that operate via a retaining mechanism, which implies a classical Koshland double-displacement mechanism and that uses at least one acidic catalytic residue Glu as nucleophile and another one generally acting as acid/base catalyst (Pell et al., J . Biol. Chem., 2004, 279(10): 9597-9605). GH 10 enzymes may be found in every kingdom, including eukaryote, prokaryote, microbial, fungal and algae. In particular embodiments, the xylanase of GH10 is extracted from the Microbial community of insect' s digestive tract.

In particular embodiments, the composition further comprises additional enzyme(s), preferably one or more or all of the following enzymes:

- a β-xylosidase;

- a glucanase;

- an arabinanase; and/or

- an esterase.

In a particular embodiment, the composition comprises a β-xylosidase, preferably a β- xylosidase of Glycoside Hydrolase family 43 (GH43). Advantageously, the β-xylosidase has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°8 (BhXyl).

Glycoside hydrolase family 43 ("GH43") family enzymes display a f i ve - b 1 aded - β- p ro pe 1 le r- like structure. The propeller-like structure is based upon a five-fold repeat of blades composed of four-stranded β-sheets. The GH43 enzymes act by inverting mechanism which impl ies that at least three catalytic amino acids are required. GH43 enzymes may be found in every kingdom, including eukaryote, prokaryote, microbial, fungal and algae. In particular embodiments, the β-xylosidase of GH43 is extracted from the Microbial community of insect ^' s digestive tract.

Alternatively or in addition, the composition comprises a GH3 β-xylosidase. Advantageously, the β-xylosidase has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 10 (Xyl_3). In a particular embodiment, the composition comprises at least one glucanase, preferably a glucanase of Glycoside Hydrolase family 8 (GH8). Advantageously, the glucanase has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 14 (Gln_8 ). Alternatively or in addition, the composition comprises a glucanase having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 20 (Gln_8-20 ).

In a further embodiment, the composition comprises an arabinanase, preferably an arabinanase of Glycoside Hydrolase family 43 (GH43). Advantageously, the arabinanase has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 12 (Abn_43).

In a further particular embodiment, the composition comprises an esterase, preferably an esterase of Carbohydrate Esterase family 1 (CE1).

CE's are a group of enzymes that catalyze the de-0 or de-N-acylation of substituted saccharides. The CAZy database has grouped CEs into 16 families, based on sequence similarity. CE1 enzymes may be found in every kingdom, including eukaryote, prokaryote, microbial, fungal and algae. Advantageously, the esterase in the composition has at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 16 (CE_ 1 - 16). Alternatively or in addition, the composition comprises an esterase having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 18 (CE_1-18). In a particular embodiment, the composition comprises a polypeptide Pax, a GH11 xylanase, preferably Xyn_l 1, and a GH43 β-xylosidase, preferably BhXyl.

In another embodiment, the composition comprises a polypeptide Pax, a GH10 xylanase, preferably Xyn_10, and a GH43 β-xylosidase, preferably BhXyl. In a particular embodiment, the composition comprises a polypeptide Pax, a GH10 xylanase, preferably Xyn_10, and a GH3 β-xylosidase, preferably (Xyl_3 ).

In another embodiment, the composition comprises a polypeptide Pax, a GH11 xylanase, preferably Xyn_l l, and a GH3 β-xylosidase, preferably (Xyl_3 ). In a particular embodiment, the composition comprises a polypeptide Pax, a GH10 xylanase, preferably Xyn_10, and/or a GH11 xylanase, preferably Xyn_l l, and a GH8 glucanase, preferably Gln_8 or Gln_8-20.

In a further embodiment, the composition comprises a polypeptide Pax, a GH10 xylanase, preferably Xyn_10, and/or a GH 1 1 xylanase, preferably Xyn_l l, a GH43 β-xylosidase, preferably BhXyl, a GH8 glucanase, preferably Gln_8 or Gln_8-20, and a GH43 arabinanase, preferably Abn_43.

In a further embodiment, the composition comprises a polypeptide Pax, a GH10 xylanase, preferably Xyn_10, and/or a GH 1 1 xylanase, preferably Xyn_ l 1 , a GH43 β-xylosidase, preferably BhXyl, a GH8 glucanase, preferably Gln_8 or Gln_8-20, a GH43 arabinanase, preferably Abn_43, and a CE1 esterase, preferably CE_1-18 or CE_1-16.

In a further embodiment, the composition of the invention further comprises a classical commercial enzyme such as a cellulase or a commercial hemicellulase cocktail.

The compositions of the invention comprise various relative ratios of the above described enzymes. In particular, the compositions may comprise between 2 % by weight and 98 % by weight of each enzyme, preferably between 2% and 80% by weight. For instance, the composition comprises about 67 % by weight of the polypeptide Pax and 33 % by weight of a GH10 xylanase, preferably Xyn_10, or GH11 xylanase, preferably Xyn_l 1.

In another embodiment, the composition comprises a same amount of each of the polypeptides. For instance, the composition comprises about 33 % by weight of the polypeptide Pax, 33 % by weight of a GH10 xylanase, preferably Xyn_10, or GH11, preferably Xyn_l 1, and 33 % by weight of a GH43 β-xylosidase, preferably BhXyl.

In a further embodiment, the composition comprises about 14 % by weight of the polypeptide Pax, 14 % by weight of a GH43 β-xylosidase, preferably BhXyl, 14 % by weight of a GH10 xylanase, preferably Xyn_10, 14 % by weight of a GH11 xylanase, preferably Xyn_l l, 14 % by weight of a GH8 glucanase, preferably Gln_8 or Gln_8-20, 14 % by weight of a CE1 esterase , preferably CE_1- 18 or CE_1-16 and 14 % by weight of an GH43 arabinanase, preferably Abn_43.

The amounts and nature of the polypeptides will be easily adapted by those skilled in the art depending e.g., on the nature of the enzymes, the biomass and the fermentable sugars to produce.

The compositions of the invention may further comprise additional polypeptide(s) exhibiting enzymatic activity, and more particularly a hemicellulosic activity. For instance, the compositions may comprise an additional arabinofuranosidase, such as arabinofuranosidase of GH51 (SEQ ID N°22 - Abf_51).

It is a further object of the invention to provide an enzymatic composition comprising a GH51 arabinofuranosidase. In this regards, the invention further relates to a composition comprising such GH51 arabinofuranosidase and at least a xylanase, and uses thereof for modifying a hemicellulose-containing biomass. More particularly, it is an object of the invention to provide an enzymatic mixture comprising the GH51 arabinofuranosidase, a GH10 xylanase, preferably Xyn_10, or a GH11 xylanase, preferably Xyn_l 1. In a particular embodiment, the composition comprises the GH51 arabinofuranosidase, a GH10 xylanase, preferably Xyn_10, a GH11 xylanase, preferably Xyn_l l, a GH43 β-xylosidase, preferably BhXyl, a GH8 glucanase, preferably Gln_8 or Gln_8-20, a CE1 esterase, preferably CE_1-18 or CE_1-16 and a GH43 arabinanase, preferably Abn_43. Polypeptides and enzymes for use in the invention can he obtained using known techniques for a variety of available sources. For instance, they may be isolated from n a t u ral 1 y - occ u rri n sources. For example, one or more polypeptides can be purified or substantially purified from naturally-occurring sources such as microbial environment of animal, human, and insect digestive tract, form soil, sea, fungi, vertebrates, etc. Alternatively, the polypeptides can be recombinant!)- produced by a host cell, such as by a recombinant bacterium or fungus. The polypeptides may also be prepared by chemical synthesis using conventional methods known per se in the art. The compositions of the invention may comprise the polypeptides in i olated and/or purified form, and/or a host cell expressing at least one of the polypeptides, and/or an extract thereof. An "extract of a host cell" designates any fraction obtained from a host cell, such as a cell supernatant, cell debris, cell walls, DNA extract, enzymes or enzyme preparation or any preparation derived from host cells by chemical, physical and/or enzymatic treatment, which is essentially free of living cells. Preferred extracts are enzymatically-active extracts.

The composition or mixture of the invention may comprise one or several host cells of the invention or extract thereof, and optionally one or several additional cells. In particular, additional cells may be cellulolytic microorganisms (e.g. cellulase, xylanase producers) or fermenting microorganisms (e.g. lactic acid producers, etc.).

In a particular embodiment, the compositions of the invention comprise one or several natural or synthetic polypeptides with hemicellulolytic activities and one or several host cells that produce recombinant polypeptides with hemicellulolytic activities, or extract thereof.

Nucleic acids

The present invention also relates to nucleic acids encoding the enzymes as disclosed above. The nucleic acids can be DNA (cDNA or gDNA), RNA, or a mixture of the two. It can be in single stranded form or in duplex form or a mixture of the two. It can comprise modified nucleotides, comprising for example a modified bond, a modified purine or pyrimidine base, or a modified sugar. It can be prepared by any method known to one skilled in the art, including chemical synthesis, recombination, and mutagenesis. More particularly, the present invention relates to

SEQ ID N° 1 that encodes the polypeptide Pax,

- SEQ ID N°3 that encodes the xylanase Xyn_l 1 ,

- SEQ ID N°5 that encodes the xylanase Xyn_10,

- SEQ ID N°7 that encodes the β-xylosidase BhXyl,

- SEQ ID N°9 that encodes the β-xylosidase Xyl_3,

- SEQ ID N° 11 that encodes the arabinanase Abn_43,

- SEQ ID N°13 and SEQ ID N° 19 that encode the glucanases Gln_8 and Gln_8-20 respectively, and

- SEQ ID N°15 and SEQ ID N°17 that encode the esterases CE_1-16 and CE_1-18 respectively.

Alternatively, the nucleic acids according to the invention may be deduced from the sequences of the polypeptides according to the invention and codon usage may be adapted according to the host cell in which the nucleic acids shall be transcribed. These steps may be carried out according to methods well known to one skilled in the art and some of which are described in the reference manual Sambrook et al. (Sambrook et a/., 2001).

The present invention further relates to an expression cassette comprising a nucleic acid as described, operably linked to one or more control sequences that direct the expression of said nucleic acid in a suitable host cell. Typically, the expression cassette comprises, or consists of, a nucleic acid according to the invention operably linked to a transcriptional promoter and a transcription terminator. The present invention also relates to an expression vector comprising such a nucleic acid or such an expression cassette. Said expression vector may be used to transform a host cell and enable the expression of the nucleic acid of the invention in said cell. The choice of the vector will typically depend on the compatibility of the vector with the host cell into which the vector is to be introduced. The vectors may be constructed by the classical techniques of molecular biology, well known to one skilled in the art.

The present invention further relates to the use of such a nucleic acid, an expression cassette or an expression vector to transform, transfect or transduce a cell. The present invention also relates to a host cell comprising such a nucleic acid, a cassette or an expression vector. The host cell may be transformed, transfected or transduced in a transient or stable manner. The expression cassette or vector is introduced into a host cell so that the cassette or vector is maintained as a chromosomal integrant or as a self -replicating extra-chromosomal vector. The term "host cell" also encompasses any progeny of a parent host cell that is not identical to the parent host cell due to mutations that occur during replication.

In a particular embodiment, the composition comprises at least one host cell expressing at least one of said polypeptides having an enzymatic activity, or an extract thereof. In some aspects, the present invention provides a host cell engineered to express one or more or all of the nucleic acids among SEQ ID N°l, SEQ ID N°3, SEQ ID N°5, SEQ ID N°7, SEQ ID N°9, SEQ ID N°l l, SEQ ID N°13, SEQ ID N°15, SEQ ID N°17, and SEQ ID N°19, or expression cassettes thereof. The host cell is desirably a bacterial cell, a mammalian cell, a fungal cell, a yeast cell, an insect cell or a plant cell. In a particular embodiment, the host cell is a fermenting microorganism, preferably selected from the group consisting of bacteria, yeasts and fungi. For instance, the host cell is selected from the group consisting of lactic bacteria. In another embodiment, the host cell is E. coll.

In a particular embodiment of the invention, the host cell comprises a nucleotide sequence encoding a polypeptide Pax having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2. In another particular embodiments, the host cell may further comprise

a nucleotide sequence encoding a xylanase, preferably a GH10 or GH11 xylanase, having preferably at least 70%, 55%, 60%, 65%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°6 or SEQ ID N°4, and/or

- a nucleotide sequence encoding a β-xylosidase, preferably a GH43 or GH3 β- xylosidase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°8 or SEQ ID N°10, and/or a nucleotide sequence encoding an arabinanase, preferably a GH43 arabinanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°12, and/or a nucleotide sequence encoding an esterase, preferably a CE1 esterase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°16 or SEQ ID N°18, and/or a nucleotide sequence encoding a glucanase, preferably a GH8 glucanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°14 or SEQ ID N°20.

In a particular embodiment, the host cell is a recombinant fermenting microorganism that expresses the polypeptide Pax and one or more polypeptides selected from the group consisting of a GH10 xylanase, a GH11 xylanase, a GH43 β-xylosidase, a GH3 β-xylosidase, a GH43 arabinanase, a CE1 esterase and a GH8 glucanase . Advantageously the recombinant fermenting microorganism is a lactic acid bacterium capable of producing lactic acid from the fermentable sugars.

Hemicellulose containing biomass degradation

The nucleic acids, cassettes, vectors, host cells, compositions and mixtures of the present invention may find use in a variety of industrial applications, including in the degradation of biomass into fermentable sugars.

The present invention thus relates to the use of such nucleic acids, cassettes, vectors, host cells, compositions and mixtures for hydrolysis of a biomass containing hemicellulose. The invention further relates to the use of nucleic acids, cassettes, vectors, host cells, compositions and mixtures of the invention for converting the hemicellulosic fraction of biomass to fermentable sugars, wherein the biomass is contacted with host cells, compositions or mixtures of the invention.

More particularly, the present invention relates to the use of the polypeptide Pax, or compositions comprising such polypeptide Pax, for the hydrolysis of a hemicellulose containing biomass.

In a particular embodiment, the polypeptide Pax may be used with one or more or all of the additional polypeptides selected from a xylanase, preferably a GH11 or GH10 xylanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°4 or SEQ ID N°6 respectively;

a β-xylosidase, preferably a GH43 or GH3 β-xylosidase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°8 or SEQ ID N°10 respectively;

a glucanase, preferably a GH8 glucanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°14 or SEQ ID N°20,

- an arabinanase, preferably a GH43 arabinanase, having preferably at least 55%, 60%,

65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°12, and

an esterase, preferably a CE1 esterase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 16 or 18.

According to the invention, the polypeptides may be used simultaneously, i.e. all the polypeptides are contacted at the same time, or almost the same time, with the biomass. Alternatively, the polypeptides may be used sequentially, i.e. the polypeptides are sequentially added to the biomass, or in two or more time.

It is another object of the invention to provide a method for modifying a hemicellulose containing biomass, wherein said biomass is contacted with a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2.

Preferably, the biomass is further contacted with a xylanase.

In a particular embodiment, the biomass is contacted with one or more or all of the additional polypeptides selected from

a xylanase, preferably a GH11 or GH10 xylanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°4 or 6 respectively; a β-xylosidase, preferably GH43 or GH3 β-xylosidase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°8 or 10 respectively;

a glucanase, preferably a GH8 glucanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°14 or SEQ ID N°20,

an arabinanase, preferably a GH43 arabinanase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°12, and

- an esterase, preferably a CE1 esterase, having preferably at least 55%, 60%, 65%, 70%,

75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 16 or 18.

The polypeptide Pax and/or the compositions of the invention may be used with any kind of biomass that comprises an effective amount of hemicellulose. Advantageously, the biomass comprises at least 10% by weight, preferably 20% by weight, of hemicellulose. In a particular embodiment, the biomass comprises at least 30% by weight of xylane and/or heteroxylane.

In a particular embodiment, the biomass is pretreated before to be contacted with the enzyme(s), host cell, mixture or composition. The pretreatment is intended to disorganize the crystalline structure to access the polymer chains of cellulose and hemicellulose and/or modify the pores in the material to allow the enzymes to penetrate into the fibers to render them amenable to enzymatic hydrolysis. Pretreatments may be mechanical, physical, chemical or biological treatments and are well-known by the skilled person. For example, vegetal biomass may be subjected to pretreatment including ammonia fiber expansion (AFEX), steam explosion, treatment with alkaline aqueous solutions, acidic solutions, organic solvents, ionic liquids (IL), electrolyzed water, phosphoric acid, microwave radiations and combinations thereof. Pretreatments that remove lignin from the biomass may increase the overall amount of sugar released from the hemicellulose.

In another particular embodiment, the mixture or composition comprises about 0.5 g to about 50 g, preferably about 0.5 g to about 20 g, of each of the polypeptides having an enzymatic activity per kilogram of biomass. Advantageously, at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of the sugars contained in the biomass are degraded.

The methods of the present invention can be practiced at any pH and temperature at which hemice! lulose can be degraded. For instance, the methods of the invention are practiced in a pil range of about 5 to about 6 and in a temperature range of about 25 to about 40° C.

Preferably, the methods of the invention are performed in a reactor. "Reactor ^" designates any device or installation or facility suitable for maintaining and transforming biomass. A reactor may comprise inlet and outlet devices to supply/collect medium, nutrients, gas, etc. The reactor may be closed or open, such as a tank.

The present invention also relates to a kit for hydrolyzing hemicellulose, comprising at least

- a polypeptide having at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°2; and

- a xylanase, preferably a GH11 or GH10 xylanase, with preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°4 or SEQ ID N°6 respectively. In a particular embodiment, the kit may further comprise a β-xylosidase, preferably a GH43 or GH3 -xylosidase , having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°8 or SEQ ID N° 10 respectively. In another embodiment, the kit may further comprise one or more or all of the additional polypeptides selected from

a glucanase, preferably a GH8 glucanase, having preferably at least 55%, 60%, 65%,

70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 14 or SEQ ID N°20,

- an arabinanase, preferably a GH43 arabinanase, having preferably at least 55%, 60%,

65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N° 12, and an esterase, preferably a CE1 esterase, having preferably at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or 100% identity to the full length amino acid sequence set forth in SEQ ID N°16 or SEQ ID N°18. The polypeptides of the kit may be used simultaneously or sequentially.

Fermentable sugars

It is a further object of the invention to provide a method of producing fermentable sugars from a hemicellulose containing biomass, comprising contacting the biomass with a host cell, mixture, composition or polypeptide(s) of the invention.

It is therefore another object of the invention to provide a method for modifying a hemicellulose containing biomass, comprising the step of:

a) contacting such biomass with a host cell, polypeptide(s) or composition of the invention ; b) optionally recovering the fermentable sugars from the modified biomass of step a), and c) optionally fermenting the fermentable sugars of step a) or b).

The recovery of the fermentable sugars includes, e.g., recovery of the fermentation broth comprising the fermentable sugars. The fermentatio broth may be used with minimum post- production processing, e.g., purification, ultrafiltration, a cell kill step, etc., and in that case it is said that the fermentation broth is used in a whole broth formulation.

Alternatively, the fermentable sugars can be recovered using further purification step(s).

In a particular embodiment, step c) of the method is implemented by contacting the fermentable sugars or biomass containing such fermentable sugars with a fermenting microorganism and producing a fermentation product.

Examples of fermentation products include, but are not limited to, biofuel ; organic acids such as lactic acid, succinic acid, citric acid, adipic acid, itaconic acid, levulinic acid, gluconic acid, acrylic acid, acetic acid, fumaric acid, malic acid, sebacic acid, terephthalic acid, furan-2,5- dicarboxylic acid, propanoic acid, hydroxypropanoic acid, hydroxyacids, ethanoic acid, glycolic acid, glutaric acid, glucaric acid or butanoic acid; diols such as butanediol, 1,2- propylene glycol, propane- 1,3-diol, or monoethylene glycol; amino acids such as aspartic acid, glutamine, glutamic acid, methionine, threonine, lysine, tryptophan or arginine; gaseous olefins such as ethylene, propylene, n-butenes, butadiene, isobutylene or isoprene; vitamins; antibiotics; isosorbide, sorbitol, xylitol, glycerol; polyhydroxyalcanoates; acetone or hydroxymethylfurfural .

Biofuel may be selected from the group consisting of ethanol, butanol, iso-butanol, propanol, isopropanol, methanol, 2,5-dimethylfuran, gamma- valerolactone. Preferably, biofuel is ethanol. Ethanol may be used as a fuel additive or extender in blends of from less than 1% and up to 100% (a fuel substitute). The ethanol-producing fermenting microorganism may be any microorganism known in the art that produces ethanol as fermentation product. Lactic acid is largely used in the food and packaging industries. Lactic acid may be obtained by fermentation, for example, using bacteria belonging to the genus Lactococcus, Lactobacillus, Streptococcus or Leuconostoc.

In a particular embodiment, step a) and step c) are performed sequentially.

Alternatively, step a) and step c) may be performed simultaneously. For instance, the mixture or composition comprises at least one host cell chosen to be able to ferment fermentable sugars and that is transformed with a nucleic acid, expression cassette or expression vector as described above, to obtain a modified fermenting strain exhibiting hemicellulolytic properties. This type of strains allows to use a single microorganism community for both hemicellulose hydrolysis and fermentation. In a particular embodiment, the fermenting microorganism is a lactic acid bacterium capable of producing lactic acid from the hydrolysate. Alternatively, the fermentation may be carried out by a second microorganism, introduced in the reactor together with the biomass and/or with the mixture/composition of the invention. Further aspects and advantages of the invention will be disclosed in the following examples, which should be considered as illustrative and do not limit the scope of this application.

EXAMPLES

Example 1: Enzyme Gene Cloning from metagenomic DNA

Standard molecular genetic techniques are used for the cloning and transformation in strain E. coli (Sambrook et al. 1989). Genes comprising sequences SEQ ID N°l, SEQ ID N°5, SEQ ID N°9, SEQ ID N°l l, SEQ ID N°13, SEQ ID N°15, SEQ ID N°17, SEQ ID N°19 and SEQ ID N°21 (nucleic acid sequence encoding an arabinofuranosidase of GH51, herein after "Abf_51"), from metagenomic DNA "termite gut Pseudacantoterm.es militaris metagenomic library" were amplified by PCR using the primers of SEQ ID N°23 to SEQ ID N°40.

PCR products were cloned via the gateway system into plasmid pDEST17 with HisTAG or pETG20A containing His and His-Thioredoxin TAG (life-technology) following protocol published by Vincentelli et al 2003. Amplified vector was purified using QIAprep Spin Miniprep Kit (Qiagen) and checked by sequencing. The following abbreviations are interchangeably used in the present disclosure:

- vector pDEST17-GH10, producing the xylanase of GH10 (Xyn_10) as set forth in SEQ ID N°6;

- vector pETG20A-GH3, producing the xylosidase of GH3 (Xyl_3) as set forth in SEQ ID N°10;

- vector pETG20A-GH3, producing the polypeptide Abf_3 as set forth in SEQ ID N°2;

- vector pETG20A-GH51, producing the arabinofuranosidase of GH51 (Abf_51) as set forth in SEQ ID N°22;

- vector pETG20A-GH43, producing the arabinanase of GH43 (Abn_43) as set forth in SEQ ID N°12;

- vector pETG20A-GH8- 14, producing the glucanase of GH8 (Gln_8-14, or Gln_8) as set forth in SEQ ID N° 14;

- vector pETG20A-GH8-20, producing the glucanase of GH8 (Gln_8-20) as set forth in SEQ ID N°20;

- vector pETG20A-CEl-16, producing the esterase of CE1 (CE_1-16) as set forth in SEQ ID N°16;

- vector pETG20A-CEl-18, producing the esterase of CE1 (CE_1-18) as set forth in SEQ ID N°18. Vector pDEST17 and pETG20A-X were transformed in E. coli Rosetta DE3 pLysS (EMD, millipore) and strains expressing the genes were selected on LB Agar + ampicillin. After transformation, transformed bacteria were spread on LB Agar medium containing ampicillin and chloramphenicol (100 and 12.5 μg/mL respectively). Positive colonies were cultivated one night at 37°C in LB medium containing ampicillin and chloramphenicol (100 and 12.5 μg/mL respectively) and used for expression culture.

The vector producing the GH11 xylanase (NpXyn or Xyn_l 1) as set forth in SEQ ID N°4 was obtained according to the technology disclosed in Vardakou et al. 2008 ("Understanding the Structural Basis for Substrate and Inhibitor Recognition in Eukaryotic GH11 Xylanases" Journal of Molecular Biology 375: 1293.)

The vector producing the GH43 xylosidase (BhXyl or Xyl_43) as set forth in SEQ ID N°8 was obtained according to the technology disclosed in Smaali et al. 2006 ("Expression in Escherichia coli and characterization of beta-xylosidases GH39 and GH-43 from Bacillus halodurans C-125" Appl Microbiol Biotechnol 73:582-90.).

Strains were grown on 2 L flask using a 1.0 L working volume of ZYP5052 auto-inducible medium containing (composition below). Temperature was maintained at 37 °C for 4h and then at 17°C for 16h.

Table 1: Composition of medium ZYP5052

Recombinant enzymes were produced in E. coli and and purified to homogeneity.

Example 2: Design and activity of compositions comprising 2 enzymes

A first enzymatic composition was developed and tested for the conversion of heteroxylans contained in a biomass. This composition comprises

- Abf_3; and

iVpXyn (or Xyn_l 1, a xylanase from family GH11)). The performance of the composition was studied in enzymatic hydrolysis assays. As substrate, 20 mg of wheat bran milled at 2 mm were distributed in 2 mL plastic tubes. The total reaction volume was 1 mL; therefore the substrate concentration in the reaction was 2% (w/v).

The enzymatic dosage employed for each enzyme was 3 mg of purified protein/g biomass and the assays were carried out in 50 mM phosphate buffer at pH 6, for 24h, at 30°C and 1100 rpm in a Thermomixer device.

The assays were performed in triplicates and reactions were stopped by heat treatment at 95 °C for 5 min.

Subsequently, the supernatants were recovered after 10 min centrifugation at 14000 rpm and submitted to reducing sugars quantification by dinitro salicylic acid (DNS) method (Miller, 1959) using a calibration curve of xylose from 0.1 to 1 g/L and measuring the absorbance at 540 mm.

In some cases monomeric sugars concentration was determined by high performance anionic exchange chromatography with pulsed amperometric detection (HPAEC-PAD).

The recovered supernatants were filtered and directly analyzed by HPAEC to quantify monomers production. Also, the supernatants were incubated for 1 h at 100 °C in presence of H2SO4 at 4% (w/v) following the NREL protocol.

Acid treatment produces complete hydrolysis of solubilized oligomers and provides an accurate value of total solubilized sugars during the enzymatic reaction.

The sugar concentration was measured using an ICS 3000 dual (Dionex, France), equipped with a Carbo-Pac PA-1 analytical and guard column. 5 μΐ of sample diluted at the appropriate concentration were injected and the separation was achieved using 500 mM of sodium acetate and 150 mM of NaOH at 1 ml/min flow rate. Calibration was achieved using monosaccharides at a concentration range from 5 to 50 mg/L.

Figure 1 illustrates the effectiveness of the tested composition: as shown, the composition has very potent hydrolytic activity, and the two enzymes cooperate to provide high yield of sugars. In particular, combining /VpXyn and Abf_3 increased of 34% the reducing sugars obtained using iVpXyn alone.

Abf_3 was primarily identified as an arabinofuranosidase enzyme (34.4 IU/mg protein on pNP- arabinofuranose). However, the results of the experimentation further showed that Abf_3 has a significant β-xylosidase activity (19.0 IU/mg protein on pNP-xylopyranose). This dual activity confers a remarkable advantage to this enzyme for the degradation of heteroxylans.

The benefits of the composition of the invention were further illustrated by comparing the above composition to a composition comprising a distinct arabinofuranosidase belonging to family GH51, SEQ ID N° 22, named Abf_51 and a β-xylosidase belonging to family GH43, SEQ ID N°8, named BhXyl

Figure 1 shows that the composition of the invention comprising iVpXyn and Abf_3 produces 9% and 19% more sugars from wheat bran than the combination of NpXyn-Abf_51 and iVpXyn- BhXyl, respectively.

In order to further demonstrate the advantages of the invention, the composition of the invention Abf_3 and iVpXyn (4 and 2mg/g respectively) was compared to a composition of three enzymes comprising xylanase NpXyn (2 mg/g), β-xylosidase BhXyl (2 mg/g), and arabinofuranosidase Abf_51 (2mg/g). Figure 2 shows that the composition of the invention, although used at 4mg, is at least as potent as the comparative composition comprising 3 enzymes at 6mg, further illustrating the unexpected potency of the invention. A composition comprising Abf_3 and Xyn_10 (a xylanase from family GH10) would have similar enzymatic activity compared to the above-described composition.

Example 3: Design and activity of compositions comprising 3 enzymes

Another enzymatic cocktail for the conversion of heteroxylans contained in a biomass containing hemicellulose, was developed, that comprises

an arabinofuranosidase from family GH3 (Abf_3);

a xylanase from family GH11 ( VpXyn or Xyn_l 1), and

- a β-xylosidase from family GH43 (BhXyl, or Xyl_43)

The enzymatic hydrolysis assays were carried out at the same conditions described for the cocktail according to Example 2.

Figure 8 illustrates the advantages of combining NpXyn, BhXyl and Abf_3, which increases in 54% and 73% the reducing sugars release when comparing to the mixture NpXyn-BhXyl and the NpXyn alone, respectively. In addition, the benefits of the presence in the cocktail of the novel enzyme Abf_3 were demonstrated by comparison with Abf_51.

The cocktail containing NpXyn, BhXyl and Abf_3 increased sugars production from wheat bran in 19% in comparison with the cocktail constituted by NpXyn, BhXyl and Abf_51. The sugars yield obtained was 27%.

HPAEC results (Table 2 below) shows the advantages of the combination NpXyn-5/iXyl-Abf_3 regarding glucose, xylose and arabinose production.

Table 2. HPAEC results for enzymatic hydrolysis assays using different enzyme combinations.

nd: not detected

Another enzymatic cocktail for the conversion of heteroxylans contained in a biomass containing hemicellulose, would have similar activity than the one described above, while comprising the following enzymes:

an arabinofuranosidase from family GH3 (Abf_3);

a xylanase from family GH10 (Xyn_10) and

- a β-xylosidase from family GH43 (BhXyl, or Xyl_43) Example 4: Design and activity of a hemicellulolytic composition comprising 7 enzymes

Complete degradation of complex biomass usually requires a wide array of enzymes. On the basis of the cocktail detailed in Example 2 (NpXyn + Abf_3), a cocktail composed of 7 enzymes was developed to enhance sugars production from non-pretreated wheat bran.

The enzymatic hydrolysis assays were carried out at the same conditions described in Example 2. A β-xylosidase, a xylanase, a glucanase, an arabinanase and an esterase were sequentially introduced in the composition of Example 2, to obtain a mixture constituted by seven enzymatic activities (figure 3).

The enzymatic dosage employed for each enzyme was 2 mg of purified protein/g biomass; therefore the cocktail contained 14% of each enzymatic component.

The cocktail was defined by seven activities: xylanase NpXyn (1) and arabinofuranosidase Abf_3 (2) from family GH3, β-xylosidase BhXyl (3) from family GH43, xylanase Xyn_10 (4) from GH10, glucanase Gln8 (5) from family GH8, arabinanase Abn43 (6) from GH43 and esterase (7) CEl-16 from family CE-1.

This composition has very potent and unexpected hydrolytic activity. Indeed, the use of such composition comprising the combination of the seven above described activities yielded 40% of sugars contained in wheat bran. The enzymatic activities of said composition have been more precisely studied:

Xylanases

The composition comprises the combination of xylanases from family GH10 and GH11, which have different substrate specificity (Pollet 2010). The supplementation of NpXyn (GHl l) with Xyn_10 (50 % of each enzyme in the mixture) increased reducing sugars production by 32%. Table 3, below, shows the results obtained by HPAEC, showing a positive effect of using the combination GHl l (iVpXyn)-GHlO (Xyn_10) in xylose and arabinose release.

Table 3. HPAEC results: effect of xylanase GH10 on the enzymatic hydrolysis of wheat bran

Monomers (mg/L) Total soluble sugars (mg/L)

Glucose Xylose Arabinose Glucose Xylose Arabinose

309 1708

NP Xyn - 34 +4 79 +26 347 +17

+125 +70

NP Xyn

537 2077

+ - 62 +2 124 +11 395 +9

+12 +20

Xyn_10 β-xylosidase

The enzyme β-xylosidase BhXyX from family GH43 was identified as the most appropriate β- xylosidase in the hydrolysis of wheat bran. Notwithstanding, another β-xylosidase from family GH3 named Xyl_3 showed a positive effect in the hydrolysis of wheat bran and it was revealed as an interesting alternative to BhXyl.

Glucanase

The main component of wheat bran is arabinoxylan (40%); however there is also a remarkable proportion of glucose (18.6%). Glucose could take part of cellulosic and/or β-glucan polymers which constitute the wheat bran cell walls.

To evaluate the effect of supplementing a glucanase enzyme Gln_8 from family GH8, an enzymatic assay was carried out using wheat bran as substrate and the conditions detailed in example 2.

A dosage of 5 mg purified protein/g biomass of NpXyn was supplemented with 5 mg purified protein/g biomass of Gln_8. NpXyn alone and Gln_8 alone produced 2.26 g/L and 0.47 g/L of reducing sugars, respectively.

The combination of both activities yielded 3.24 g/L of reducing sugars, which confirms the relevant role of this activity in the cocktail and suggests a synergistic effect between both enzymes. HPAEC analysis confirms the great improvement regarding total solubilized glucose (Table 4, below).

Another glucanase from the family GH8, named Gln_8-20 showed a positive effect as well and represent an alternative to the use in the cocktail of Gln_8.

Table 4. HPAEC results: effect of glucanase activity on the enzymatic hydrolysis of wheat bran.

Monomers (mg/L) Total soluble sugars (mg/L)

Glucose Xylose Arabinose Glucose Xylose Arabinose

NpXyn nd 339 14 97 2305 764

NpXyn

+ nd 487 174 835 2407 949

Gln_8 Arabinanase

Arabinanase enzymes hydrolyze internal bonds in the arabinan chains. In herbaceous biomass xylan is typically monosubstituted by arabinose residues. Nevertheless, according to the literature and the high proportion of arabinose in the wheat bran, it is not unlikely to find arabinan chains in the wheat bran hemicellulose.

In this context, the effect of adding an arabinanase activity was studied. The enzyme Abn_43 (family GH43), identified as an arabinan- active enzyme was supplemented to the mixture of xylanases iVpXyn + Xyn_10 using a dosage of 3 mg purified/g biomass for each enzyme. HPAEC results (table 5) show a clear improvement in sugars production by adding Abn_43.

Table 5. HPAEC results: effect of arabinanase on the enzymatic hydrolysis of wheat bran.

The effect of the arabinanase Abn_43 was also evaluated in combination with the enzymes already selected for the main cocktail (xylanases iVpXyn and Xyn_10, and glucanase Gln_8), and in combination with an arabinofuranosidase (Abf_3), that could show a synergistic effect with the arabinanase.

A dosage of 3 mg/g substrate for each enzyme was used. Esterase

The composition comprises the carbohydrate esterase CE_1-16 (family CEl). Its positive effect was demonstrated in enzymatic hydrolysis assays under the conditions described in example 2. A dosage of 2 mg purified protein/g biomass of CE_1-16 was supplemented to the composition constituted by two xylanases (iVpXyn and Xyn_10), glucanase Gln_8, arabinanase Abn_43, β- xylosidase BhXyl and arabinofuranosidase Abf_3.

The addition of CE_1-16 improved reducing sugars release by 7%.

Other esterase from family CEl and named CE_1-18 also showed a positive effect on the enzymatic hydrolysis of wheat bran and represents an alternative to the use in the composition of CE_l-16. Once defined the composition optimizing sugars production from wheat bran, a supplementary enzymatic hydrolysis assay was carried out to compare the performance of the novel enzyme Abf_3 to classical arabinofuranosidase. In these experiments, started in parallel at the conditions described above, two different arabinofuranosidases, a classical arabinofuranosidase Abf_51, or the arabinofuranosidase Abf_3, were introduced in the enzymatic mixture constituted by iVpXyn, BhXyl, Xyn_10, Gln_8, Abn_43 and CEl- 16 (also called "Cocktail" in Figure 4).

Figure 4 shows the results for these experiments. The presence of Abf_3 in the composition improves the production of reducing sugars by 8.1 % comparing to the Abf_51, illustrating the advantages of using this polypeptide instead of other arabinofuranosidases.

Example 5: Comparisons with a commercial composition

The performance of the composition of the example 4 (iVpXyn, Abf_3, BhXyl, Xyn_10, Gln_8, Abn_43 and CEl- 16) was compared with two commercial preparations from Novozymes: (1) the mixture of Celluclast® (a cellulase) and NS50030 (a xylanase); and

(2) the commercial hemicellulosic cocktail Cellic HTec2®. This product is described as endoxylanase with high specificity toward soluble hemicellulose and a cellulase background, and it is featured to convert hemicellulose to fermentable sugars.

Three experiments, containing the three different compositions, were started in parallel and in triplicates at the same conditions described in example 2.

In order to compare the performance of the three compositions, the same protein loading was employed in all experiments. The method BCA was used to determine the protein content.

Figure 5 shows the results obtained by DNS analysis of supernatants recovered after the 24h reaction. The composition of the example 4 according to an embodiment of the invention (also called "Optimal Cocktail" in Figure 5 and in Figure 6) constituted by seven enzymatic activities improved the reducing sugars production from wheat bran by 19% and 6% comparing to Celluclast-NS50030 and Cellic HTec2®, respectively. Supernatants from the Cocktail of the invention and Cellic HTec2® reactions were submitted to HPAEC analysis (Table 6). The main advantage of the Cocktail of the invention derived from this invention was the great increase in monomeric xylose and arabinose from wheat bran. This result confirms the advantages to combine the arabinofuranosidase (Abf_3) to an additional β- xylosidase (BhXyl). Table 6. HPAEC results: comparison of the Cocktail of the invention and Cellic HTec2 on the enzymatic hydrolysis of wheat bran.

The potential of the Cocktail of the invention to complement a classical cellulase (Celluclast) was also examined.

Three experiments were started in parallel and in triplicates at the same conditions described in example 2. In one of them, only 5 mg protein/biomass of Celluclast® was added. In the other two Celluclast® was supplemented with an equal dosage of Cocktail of the invention and Cellic HTec2®.

As shown in figure 6, supplementation of Celluclast® with a hemicellulase cocktail improved greatly the reducing sugars production. In addition, the Cocktail of the invention improved reducing sugars production by 24% comparing to Cellic HTec2®, obtaining a sugars yield of 47%. HPAEC analysis (Table 7) confirms the advantages of the Cocktail of the invention, which significantly improved the release of monomeric xylose and arabinose from the heteroxylan contained in wheat bran.

Table 7. HPAEC results: Effect of cellulase supplementation with hemicellulolytic cocktails on the enzymatic hydrolysis of wheat bran.

Monomers (mg/L)

Glucose Xylose Arabinose

Celluclast® 0.56 0.45 0.13

Celluclast® +

0.85 1.65 0.25

Cellic HTec2®

Celluclast® +

Cocktail of the 0.80 2.98 0.56

invention Example 6: Evaluation of the composition comprising seven activities on a pretreated substrate

In bioconversion processes from lignocellulosic biomass a pretreatment is usually required to increase the accessibility of the enzymes to carbohydrates and optimize sugars yields. The performance of a hemicellulolytic composition derived from example 4 and constituted by /VpXyn, Abf_3, BhXyl, Xyn_10, Gln_8, Abn_43 and CEl- 16 was further evaluated on a pretreated substrate. Wheat bran was submitted to a physico-chemical treatment. 20 mg of wheat bran were incubated for 30 min at 160°C in presence of 0.2% H2SO4 (w/w) (1 mL total volume). A pH of 1.9 was determined at the end of the process. The pretreated material was dried at room temperature and subsequently submitted to an enzymatic hydrolysis using the composition of example 4 (2 mg purified protein/g biomass for each enzyme). The enzymatic hydrolysis conditions were the same described in example 2, but using the pretreated wheat bran as substrate. A control enzymatic hydrolysis using the non-pretreated wheat bran as substrate was started in parallel.

The figure 7 shows the results for this experiment. The acid pretreatment produces itself solubilization of sugars contained in wheat bran up to 4.6 g/L. Followed by an enzymatic hydrolysis using the composition of example 4, a total amount of 8,3 g/L reducing sugars was obtained, which corresponds to a sugars yield of 70%.

REFERENCES

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