OF THE The compound of Formula I or its any salt form produced by the inventive method is used as an immunosuppressant therapeutically. Compound of Formula I is also referred as FK520 This agent inhibits the proliferative response of lymphocytes to alloantigen stimulation, and a variety of T cell associated immune reaction. The compound suppresses immune responses in vivo as well as in vitro. The compound can be further chemically modified to another form which is useful in the treatment of psoriasis and does not have immunosuppressive activity.

Formula I The prior art literature does not disclose production of compound of Formula I or its any salt form, by solid substrate fermentation or solid state fermentation with fed-batch technique.

SUMMARY OF THE INVENTION The present invention provides a novel method for production of compound of Formula I or its salts.

In preferred embodiments, the invention provides a fermentation process in which the compound of Formula I or any of it's salt form, is produced on solid nutritious matrix. The fermentation is also carried out in fed-batch mode to increase the productivity/yields of the final product. The fermentation is also carried out in a contained bio-reactor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Definitions "Solid state fermentation" or "solid state cultivation" : The term"solid state fermentation"or"solid state cultivation", sometimes referred to as"semi-solid state

fermentation"as used herein, means the process of fermenting microorganisms on a solid medium that provides anchorage points for the microorganisms in the absence of any freely flowing substance. The amount of water in the solid medium can be any amount of water. For example, the solid medium could be almost dry, or it could be slushy. A person skilled in the art knows that the terms"solid state fermentation"and"semi-solid state fermentation"are interchangeable.

"Fed-batch fermentation"or"fed-. batch technique" : The term fed-batch fermentation as used herein, means a fermentation process carried out where substrate or nutrients are added in small increments as the fermentation progresses. The substrate or nutrient is added in small increment that would encourage the production of secondary metabolites, because some secondary metabolite production is inhibited by high concentrations of substrate or substrates, so this method would encourage the production of such metabolites. Supplement of nutrients at a time when the initially fed nutrient are consumed by the microorganisms or culture also help in providing more energy to the microorganism which in turn increases the overall production of the secondary metabolites.

The term"bioreactor"as used herein, means a device capable of holding fermentation media inoculated with microorganism and carrying out the process of solid state fermentation in a contained manner. A bioreactor can be used to grow any microorganism capable of growing under specified

conditions in a contained environment. Some examples of microorganisms capable of growing in a bioreactor are fungi, yeast and bacteria.

The present invention discloses a process for production of compound of Formula I or its any salt form, by culturing a microorganism capable of producing such compound on solid nutrient matrix wherein, optionally the nutrients are fed in adequate quantities during the growth of the culture so that the production of the product increases significantly.

The instant invention discloses a process for the manufacture of compound of Formula I and its salts by solid substrate fermentation.

The solid substrate fermentation is carried out using Streptomyces hygroscopicus.

The solid substrate for fermentation is selected from wheat bran, wheat rava, oat meal, broken wheat, boiled rice, rice bran, rice rava, beaten rice, maize bran, maize grits, oat bran, bagasse, tapioca residue, soy grits, soy flakes, rice flakes, ceramic beads, glass beads, sponge or a mixture of two or more of these.

The carbon source for feeding is selected from glucose, sucrose, starch (maize, wheat, tapioca, potato), modified starch, maltose, matto-dextrin, soybean oil, acetate or a mixture of two or more of these.

The nitrogen source for feeding is selected from ammonium sulphate, dried yeast, ammonium nitrate, sodium nitrate, bacteriological peptone, yeast extract, casein hydrolyzate, soy

peptone, soy flour, cotton seed flour, corn steep liquor or a mixture of two or more of these.

The solid substrate fermentation is also carried out in a fed- batch mode.

The feeding for fed-batch fermentation is done at the beginning of the fermentation or at intervals throughout the fermentation.

The first aspect of the invention is production of compound of Formula I or its any salt form. The compound is afforded by culturing Streptomyces sp. on solid nutrient matrix e. g. wheat bran, wheat rawa, broken wheat, boiled rice, rice bran, rice rawa, beaten rice, rice flakes, maize bran, maize grits, oat bran, bagasse, tapioca residue, soy grits, soy flakes, ceramic beads, glass beads, sponge or a mixture of one or more of these. The product is then purified by conventional techniques comprising filtration, centrifugation, chromatography, extraction, distillation, concentration, precipitation, crystallization and drying.

The second aspect of invention is production of compound of Formula I or its any salt form. The compound is afforded by culturing Streptomyces sp. on solid nutrient matrix e. g. wheat bran, oatmeal, soybean meal, wheat flour, soybean flakes, maize bran etc. The culture is then fed with nutrients to increase production of the final product. The product-is purified by conventional techniques comprising filtration, centrifugation, chromatography, extraction, distillation, concentration, precipitation, crystallization and drying.

The advantages of the present invention over the other reported methods are: (i) cost effective process (ii) higher productivity of compound of Formula I with feeding (iii) self-contained bioreactor decreases hazardous exposure and risk of contamination.

The following Examples further illustrate the invention, it being understood that. the invention is not intended to be limited by the details disclosed therein.

EXAMPLES EXAMPLE 1 A grown slant of Streptomyces hygroscopicus was taken and 5ml of distilled water was added. It was shaken thoroughly and 4ml of this spore suspension was used for the inoculation of 400ml seed medium taken in 2000 mi conical flask. The composition of seed medium is as follows: Dextrose = 20g/L Yeast extract 15g/L Malt extract lOg/L Agar = 5g/L pH of this medium is adjusted to 6.5 after making up the volume with water. The seed flasks were grown at 28°C for 4 days and used as an inoculum for solid state fermentation.

Solid state fermentation: lOgm of different raw materials as given below were taken in separate petri plates. Adequate amount of water was added and sterilized at 121 deg C for 30 minutes. 10 mi inoculum from 4 day old seed medium was added.

The entire substrate was mixed properly with the inoculum and incubated at 28 deg C for 7 days. Following results were obtained. Substrates mg/kg substrate Wheat bran 1726 Broken wheat 3590 Wheat rawa 479 rice rawa 392 oat meal 588 Maize grits 516 soy grits 443 Maize bran 261 rice flake 832

EXAMPLE 2 Solid state fermentation was conducted as in Example 1 using 75 g ceramic beads as the solid support in a petri-plate, 15 mL of Streptomyces hygroscopicus inoculum grown in seed medium was added. The result obtained is given in the table below. Solid substrate FK520 Mg/kg substrate Ceramic beads 604.5

EXAMPLE 3 Solid state fermentation was conducted as in Example 1 using different solid supports in combination. l0gm of the combination substrates were taken in petri plate and 10ml of

Streptomyces hygroscopicus inoculum grown in seed medium was added. The results obtained are given in the table below. Solid substrates FK520 mg/kg substrate Wheat bran + broken wheat + beaten 3720 rice Wheat bran + broken wheat + red rice 3860 Wheat bran + broken wheat + brown rice 2620

EXAMPLE 4 Solid state fermentation was conducted as in Example 3 using a mixture of wheat bran, broken wheat and beaten rice.

10gm of this substrate is taken in petri plate and 10m ! of Streptomyces hygroscopicus inoculum grown in seed medium was added along with a liquid nutrient feed consisting of glucose and yeast extract. The feed was added every alternate day up to 4th day. Solid substrates FK520 Mg/kg substrate Without feed 3860 With feed 4830

5 Seed inoculum of Streptomyces hygroscopicus is obtained as explained in Example 1. 3. 5L of this inoculum was used for

inoculating 35 L of the same seed medium taken in a 50L fermenter. This is grown for 48 hr at 28°C. This is used as an inoculum for solid state fermentation. 15 kg of substrate mixture consisting of wheat bran, oatmeal and rice flake was loaded into a bioreactor having 22600 cm2 surface area. The bioreactor was sterilis. ed at 121 deg C for 1 to 2 hours using steam. After the sterilization the temperature of the solid substrate was brought down to 28 deg C. 15 L of the above inoculum was added to the solid substrate along with 2 L of glucose and dried yeast feed and mixed. This was incubated at 27 to 29 deg C. On 2nd and 4th day 2 L of the above feed was added to the solid substrate matrix and mixed well. The entire biomass along with the solid substrate was harvested on 7th day and processed to get pharmaceutically acceptable grade of FK520.