title: Improvement of L-lactic acid production by osmotic-tolerant mutant of Lactobacillus casei at high temperature.
abstract: L-Lactic acid production by Lactobacillus casei was used as a model to study the mechanism of substrate inhibition and the strategy for enhancing L-lactic acid production. It was found that the concentration of cell growth and L-lactate decreased with the increase of glucose concentration and fermentation temperature. To enhance the osmotic stress resistance of the strain at high temperature, a mutant G-03 was screened and selected with 360 g/L glucose at 45°C as the selective criterion. To further increase the cell growth for lactic acid production, 3 g/L of biotin was supplemented to the medium. As a result, L: -lactate concentration by the mutant G-03 reached 198.2 g/L (productivity of 5.5 g L(-1) h(-1)) at 41°C in a 7-L fermentor with 210 g/L glucose as carbon source. L: -Lactate concentration and productivity of mutant G-03 were 115.2% and 97.8% higher than those of the parent strain, respectively. The strategy for enhancing L: -lactic acid production by increasing osmotic stress resistance at high temperature may provide an alternative approach to enhance organic acid production with other strains.
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University, #1800 Lihu Road, Wuxi 214122, JiangSu Province, People's Republic of China. xyge168@163.com
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Ge
authors.forename: Jian
authors.initials: J
authors.lastname: Yuan
authors.forename: Hao
authors.initials: H
authors.lastname: Qin
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Zhang
mesh_terms: D003470:Culture Media / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D019344:Lactic Acid / Q000096:biosynthesis*; D007780:Lacticaseibacillus casei / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D009154:Mutation; D009995:Osmosis; D013312:Stress, Physiological
chemical_list: D003470:Culture Media; D019344:Lactic Acid; D005947:Glucose