Background of the Invention The control of algae in industrial and commercial water systems, cooling towers, swimming pools, etc., as well as in lakes, ponds, streams, etc. is of importance for economic and aesthetic reasons. It is also desirable to minimize environmental and ecological side effects common to many of the substances which are currently used to control the growth of unwanted algae.

Natural and synthetic antibiotics are legion in the art; however, we have found no disclosure of their use as an algicide.

Disclosed herein are a series of antibiotics which are surprisingly effective in the control of algae in water systems, aquaria, lakes, ponds, etc. These antibiotics are the natural product of microbiological fermentation, thus they are biodegradable and less likely to cause untoward environmental effects. An additional advantage is that this series of antibiotics has been shown to be nontoxic to all fish and other aquatic fauna tested to date.

Information Disclosure US 4,938,958 (Niira, et al) discloses an antibiotic zeolite and its use as an anti-algal in water systems, and when incorporated into paints, adhesives, paper, etc.

US 4,613355 (Omura, et al) discloses an antibiotic isolated from Actinomycete, having activity as a herbicide. The patent also discloses the use of this antibiotic against aquatic plants which is broadly defined to include algae. US 4,402,971 (Edwards) describes the isolation of a natural toxin from Scytonema spp. and it use in the treatment of water supplies, swimming pools, etc.

US 3,574,697 (Welcher) describes haloalkene bisthiocyanates which are asserted to be useful against Chlorella (green algae).

Gauthier, A., et al., Mol. Gen. Genet. 214:192-197 (1988) report the mapping of genes conferring chloroplast resistance to erythromycin, spiramycin, and streptomycin in Chlamydomonas.

Gleason, F.K. and CA. Baxa, FEMS Microbiology Letters 33: 85-88 (1986) report that cyanobacterin is toxic to cyanobacteria at 5μM and that cyanobacterin is toxic to, or can also be used to inhibit the growth of, photosynthetic eukaryotic organisms. Krajcovic, J., et al., Antimicrobial Agents and Chemotherapy 33:1883-1889 (1989) report that the simultaneous treatment of chlora phenicol or rifampin with quinolones or

coumarins resulted in a decrease in the potency of DNA gyrase inhibitors in Euglena gracilis.

Macor, M. and Ebringer, L., Folia-Microbiol (Praha) 33: 314-322 (1988) report that the treatment of Euglena gracilis with a variety of antibiotics either had no effect or resulted in the elimination of chloroplasts from the organism. Pattanaik, U. and Singh, P.K., Ada. Microbiol. Hung. 35:81-88 (1988) report that rifampicin but not actinomycin suppressed growth of Nostoc muscorum.

Shahan, T.A., and Pore, R.S., Antimicrobial Agents and Chemotherapy 35:2434-2435 report the effects of gentamicin on Chlorella protothecoides.

EP 0 415 641 (Lange, et al) describes N-aryl or N-aryloxy-butyramides which are asserted to be useful against green and blue-green algae.

Japanese patent applications 86/120066 and 86/120067, as reported in Derwent Abstracts 88-016585 and 88-016586, respectively, describe the use of an agent containing trialkyl- sulphonium (in 88-016585) and (3-amino-3-carboxy propyl)methyl phosphine (in 88-016586) to selectively control harmful green and blue-green algae without adversely effecting seaweed (laver).

However, none of these references teach or suggest the use of the bacterial or fungal antibiotics described herein to control algal growth.

Summary of the Invention The present invention relates to a method of controlling the growth of algae comprising: exposing the algae to an effective amount of a compound selected from the group consisting of lincomycin, spectinomycin. pirlimycin, clindamycin, or combinations thereof. The preferred method uses the compound lincomycin or spectinomycin; more preferred is the method where the compound is a combination of lincomycin and spectinomycin; most preferred is the method where the combination of lincomycin and spectinomycin is combined in a 1:4 ratio of lincomycin to spectinomycin.

Following the method of the invention, lincomycin, spectinomycin, pirlimycin, clindamycin, or combinations thereof are used in any effective amount, preferably in the range of 0.001 to about 1 gram per liter. More preferred is 0.05 to 0.1 gram per liter; most preferred is 0.006 to 0.01 gram per liter. It is preferred that the alga to be controlled are from the green and blue-green genus.

Detailed Description of the Invention The compounds which are useful in the method of the invention include the antibiotics lincomycin, spectinomycin, pirlimycin, clindamycin, and their analogs, as well as combinations thereof. The chemical names of representative compounds are shown in Table 1 and the chemical structures of representative compounds are shown in the Chart A.

Included within the compounds useful in the method of the invention are the chemica ¹

analogs of lincomycin, spectinomycin, pirlimycin, and clindamycin. Those skilled in the art will readily recognize that numerous analogs of these antibiotics are known which are suitable for use in the method of the invention and may be readily substituted therein.

The antibiotics useful in the invention may be obtained from a culture of the source microbiological organism following procedures of fermentation and extraction well known in the pharmaceutical arts. Preferably, however, these compounds, or their equivalents, are readily obtained from commercial sources. For instance, the compounds lincomycin, spectinomycin, pirlimycin, and clindamycin are available from The Upjohn Company, Kalamazoo, MI; spectinomycin may be obtained from Abbott Labs, Abbott Park, IL. In addition, some of these compounds are commercially available in combination. For instance, the combination of lincomycin and spectinomycin may be obtained from The Upjohn Company. The preferred compounds for use in the method of the invention are lincomycin, spectinomycin, and clindamycin. If combined, the preferred combination is of lincomycin and spectinomycin, the preferred ratio of combination appears to be a 1 :4 ratio of lincomycin to spectinomycin. When used in the method of the invention the compounds are suitable to prevent, inhibit, eliminate, or otherwise control the growth of algae. Algal growth can occur under a wide range of environmental conditions, and thus the method of the invention may be useful whenever it is desirable to prevent, inhibit, eliminate, or control such growth. More typically, the growth of algae is one of a primarily economic and/or aesthetic concern where such growth is unwanted and potentially damaging to equipment or other aquatic organisms. The growth can occur in aquatic environments (e.g. lakes, ponds, streams) and other bodies of water and water systems (e.g. commercial and industrial baths, tanks, towers, lagoons, cooling systems, etc.) as well as private and public swimming pools, water treatment facilities, etc. Treatment following the method of the invention may be accomplished either prior to, and/or during, and/or after the use of the water so treated. In those situations where desirable plant or animal species may be present, administration of these compounds following the method of the invention has an additional advantage in that doses effective to control algae generally have no adverse effect on fresh water fish and plants or on sea water invertebrates, anemones, hermit-crabs, symbiontic- crabs. and annelids, etc. The compounds of the invention are administered in any dose effective to prevent, inhibit, eliminate, or otherwise control the growth of algae. For instance, we have found that the combination of lincomycin/spectinomycin in doses in the range of 0.005 to 0.01 gram per liter are effective to eliminate the growth of green algae from aquaria. We have also found that pirlimycin at doses as low as 0.032 grams per liter are effective in inhibiting the growth of Selanastrum. Typically, however, an effective dose is found in the range of 0.001 to about 1 gram per liter. More typically, a dose of 0.005 to 0.05 gram per liter is effective. The preferred

dose is 0.006 to 0.01 gram of lincomycin/spectinomycin per liter. A person skilled in the art will recognize that antibiotic concentrations effective against one species or genus of algae may be readily adapted for use in a different species or genus. Experiments designed to show such effectiveness may be readily designed and easily completed by the skilled person and require no special mention. In addition, the effective minimum inhibitory concentration made be readily determined under suitable conditions following techniques and protocols well known in the art and again require no special mention.

The compounds used in the method of the invention are, generally, hygroscopic and hydrophilic and thus may be easily solubilized where the algal growth to be prevented, inhibited, or controlled is in an aqueous system. Thus, when used following one method of the invention, effective treatment may be obtained when the compounds are simply dispersed onto the surface of system to be treated and/or stirred or otherwise mixed, or allowed to dissolve, into the aqueous system or environment.

In some circumstances, however, it may be advantageous to first combine the antibiotic compound with one or more formulation agents. The presence of a formulation agent allows the antibiotic compound to be more uniformly distributed or easily dispersed, to increase or decrease dissolution or absorption, and may include agents useful to control pH and acidity, etc. The compounds may be first mixed, blended, dissolved, etc. with one or more of these formulation agents. The antibiotic compound, either with or without a formulation agent, may also be combined with other treatment modalities used to control algae. For example, in situations where cupric sulfate is effective to control some organisms, it may be suitable to add the chemical control agent in combination with the antibiotic compound of the invention.

"Algae" means any nonvascular plant having chlorophyll. Algae are chiefly, but not exclusively, found in aquatic environments. In some organisms the chlorophyll may be masked by other, e.g. brown or red, pigments.

"Controlling" the growth of algae means to prevent, inhibit, and/or eliminate the presence of algae from the treated environment.

By following the foregoing description, it will be apparent to one skilled in the art how the method of the invention may be readily adapted or modified for a particular application. Without limiting the foregoing, more detailed embodiments are listed below.

Example 1 Effect of lincomycin/spectinomycin combination on CYANOPHYCEA (Blue- Green Algae) a) In the first part of this experiment two clean aquaria are used. Each aquarium contains 35 liter fresh water and is colonized with blue-green algae. The water is kept at a temperature of 21°C and is aerated 24 h/day. When the aquaria show growth of blue-green algae on the glass walls, one is treated with lincomycin/spectinomycin (LINCO-SPECTIN

SOLUBLE POWDER, The Upjohn Company) at a dose of 6.6 mg/liter. The aquaria are followed for 14 days. After two days the algae in the treated aquaria are shrivelling and sloughing off. The algae in the control aquaria are growing well. b) For the second part of this experiment, six clean aquaria are used. Each aquarium contains 35 liter fresh water kept under constant aeration at a temperature of 21°C. The aquaria are paired and each paired set has the same fresh water aquarium plants placed inside. Of each pair, one is control and one is treated. The treatment groups receive lincomycin/spectinomycin combination at a rate of 6.6 mg/liter, 66 mg/liter, and 660 mg/liter water. The experiment is followed for 14 days. After 14 days there was no growth of blue-green algae at any of the dosages studied. In addition, no adverse effects to the aquarium plants were observed. The control aquaria show healthy growth of algae.

Example 2 Effect of lincomycin/spectinomycin combination on CHLOROPHYCEA (Green Algae) a) For the first part of this experiment eight clean aquaria were used. Each aquarium has a sandy bottom and contains 60 liter fresh water at a temperature of 21°C. The water is aerated 24 h/day. Half of the volume of each aquaria (30 liter) was renewed twice within 14 days. The aquaria are paired and each paired set has the same fresh water aquarium plants placed inside. Four of the aquaria serve as controls; four receive lincomycin/spectinomycin combination (LINCO-SPECTIN SOLUBLE POWDER, The Upjohn Company) at a rate of 6.6 mg/liter water. The treated groups did not receive additional antibiotic when their water was renewed. The experiment is followed for 14 days. After two days the presence of green algae is noted on the glass sides of the control aquaria. The treatment aquaria show no growth of green algae after 14 days. At the termination of the experiment no adverse effects on the aquarium plants is seen. b) For the second part of the experiment a 120 liter fresh water aquarium is used. This aquarium has no sand on the bottom and contains a variety of fresh water aquarium plants and 100 fresh water fish. This aquarium has a preexisting colony of green algae on its glass sides. The water temperature is 21°C and the water is constantly aerated. Lincomycin/spectinomycin is added at a rate of 6.6 mg/liter. After two days the green algae has died off. c) For the third part of the experiment three aquaria are employed. Each contains 35 liter fresh water, a variety of fresh water aquarium plants, a sandy bottom, water temperature of 21°C, and constant aeration. These aquaria are colonized with green algae. At day one lincomycin/spectinomycin is added at the rate of 6.6 mg/liter, 66 mg/liter, and 660 mg/liter, each dose to one of three aquaria. After seven days the aquaria are renewed with fresh water containing the respective dose of antibiotic. After 14 days there was no growth of green algae at any of the dosages studied. In addition, no adverse effects to the aquarium plants were

observed.

Example 3 Effect of Pirlimycin Hydrochloride on Selenastrum capricornutum

The culture medium used in this experiment is an algal medium prepared with distilled deionized water and adjusted to pH 7.5 0.1 with 0.1 N hydrochloric acid or sodium hydroxide after autoclaving. The composition of the algal medium is shown in Table 2. Stock cultures of S. capricornutum are grown in 125-ml flasks and maintained under test conditions for at least 5 days prior to test initiation. Test conditions were agitation at a rate of 100 rpm, temperature 2 - 25°C, and continuous illumination at 400-450 footcandles. The test solution concentrations were 0.50, 0.25, 0J3, 0.064, 0.032, 0.016, and 0.008 mg pirlimycin hydrochloride (The Upjohn Company) per ml algal medium. 50 ml test solutions were prepared, in triplicate, at each concentration. Control was algal medium alone. Under aseptic conditions the test solutions are inoculated to a density of 1 x 10 ⁴ cells/ml. Cell counts are taken every 48 hours for 14 days. The results of this study show that pirlimycin is toxic (only cell fragments present) to green algae at the highest concentration tested. At concentration as low as 0.064mg/ml, pirlimycin causes chlorosis and some toxicity (some cell fragments present). At concentrations of 0.032 mg/ml and above pirlimycin inhibits algal growth as measured by cell density.

CHART A

Lincomycin

10

Spectinomycin

20

Pirlimycin

35 Clindamycin

TABLE 1

COMMON NAME CHEMICAL NAME

Lincomycin Methyl 6,8-dideoxy-6-[[(l-methyl-trαπj-4-propyl- -2- pyrrolinyl)carbonyl]amino]- 1 -thio-D-erythro-α- -galacto- octopyranoside

Spectinomycin Decahydro-4cx,7,9-trihydroxy-2-methyl-6,8-bis(methylamino)- [2R-(2α,4αβ,5αβ,6β,7β,8β,9α,9ααJ0αβ)]-4H-pyrano [2,3- b][ 1 ,4]benzodioxin-4-one

Pirlimycin Metliyl 7-chloro-6J,8-trideoxy-6-[[(4-ethyl-2- piperidinyl)carbonyl]amino]-l-thio-(2S-cw)- -threo-α-D-galacto- octopyranoside

Clindamycin Methyl 7-chloro-6,7,8-trideoxy-6-[[(trα/w- 1 -methyl-4-propyl-Z.-2- pyrrolidinyl)carbonyl]amino]- 1 -thio- -threo-α- -galacto- octopyranoside

TABLE 2

COMPOSITION OF ALGAL GROWTH MEDIUM

5 COMPOUND CONCENTRATION

NaN0 ₃ 25.5 mg/L

MgCl ₂ 6H ₂ 0 12.164 mg/L

CaCl ₂ 2H ₂ 0 4.41 mg/L

10 MgS0 ₄ 7H ₂ 0 14.7 mg/L

K ₂ HP0 ₄ 1.044 mg/L

NaHC0 ₃ 15.0 mg/L

H ₃ BO ₃ 185.52 μg/L

MnCl ₂ H ₂ 0 415.61 μg/L

15 ZnCl ₂ 3.271 μg/L

CoCl ₂ 6H ₂ 0 1.428 μg/L

CuCl ₂ 2H ₂ 0 0.012 μg/L

Na _j MoO^H _j O 7.26 μg/L

FeCl ₃ 6H ₂ 0 160.0 μgA.

20 Na ₂ EDTA 2H ₂ 0 300.0 μg/L