METHOD OF PRODUCING LACTIC ACID Russian patent published in 2017 - IPC C12P7/56 C12N1/20 

FIELD: biotechnology.

SUBSTANCE: invention relates to biotechnology. Method of producing lactic acid in fermentation mediums involves preparation of sowing, fermentation and additional mediums with carbohydrate, protein and salt, containing salts of potassium, magnesium, manganese, ammonium, parts, cultivation in sowing flasks and fermenter on main fermentative medium of producer-strain with introduction of additional fermentative medium in process of cultivation, while maintaining pH value, temperature of cultivation, mixing. Wherein fermentative accumulation medium is loaded into fermenter, volume of which is 5–10 times greater than volume of main fermenter, duration of accumulation fermentation is 12–24 h. Accumulated biomass is separated in centrifugal field with separation factor 2,700–3,000, resuspended in fermentative addable medium, transferred into main fermenter, where it is cultivated for 2–3 hours with simultaneous supply of additional medium with titration agents to maintain pH with ammonia water in case of producing ammonium lactate or with sodium hydroxide solution in case of producing sodium lactate. Then all content of fermenter is fully discharged and producer biomass is separated from culture fluid in centrifugal field with separation factor 2,700–3,000. Producer biomass is resuspended with next portion of fermentative addable medium and cultivated in next cycle. Number of cycles in main fermentation is 10–20 cycles, fugate after separating producer biomass is used for further processing into lactic acid or salt of lactic acid. Producer-strain is represented by lactic acid microorganisms with rate of lactic acid formation no less than 5 g/l·h in periodic process of cultivation. Accumulation, addable and additional fermentation nutrient mediums contain fermentolysate of starch-containing material as source of carbohydrates, obtained from starch-containing grain material or bran by wet hydro-mechanical-acoustic grinding with separation by fractionation of starch A and B, with their fermentative full hydrolysis to glucose, in amount of 4–12 % in fermentation accumulation medium, 2–8 % in fermentation addable medium and no less than 40% in additional medium by glucose, respectively.

EFFECT: invention provides high rate of fermentation of sugars and accumulation of high concentration of lactic acid in culture fluid.

1 cl, 10 ex