Screening The Bacteria Fermenting Xylose To L-lactic Acid At High Temperature And Optimizing Conditions Of Fermentation

This paper developed the study on lactobacillus to produce L- lactic acid using the xylose at high temperature. First,126 samples were gathered in the natural environment in which grew to the lactobacillus . Then had carried on the screening experiment of lactobacillus,and 2 lactobacillus with higher and steadier output of L-lactic acid were selected,and culture conditions of seed and influential factors of L-lactic acid fermentation were explored. Simultaneously producing L- lactic acid using corncob was elementary discussed. Finally indicated, the best seed raise conditions of T11-1 and O7-7 is: 100mL seed culture mudium in 200 mL triangle bottle ,16 hours in shake bed;It′s best component fermentation medium is (g/L): peptone 5.0,yeast extract 3.0, beef paste 2.0,xylose 60.0,K₂HPO₄ 2.0,MnSO₄·4H₂O 0.04,MgSO₄·7H₂O 0.20,FeSO₄·7H₂O 0.05;The best fermentation condition is: 150mL fermentation medium in 250mL bottle,vaccinates 10 %, 48 hours in shake bed under 46℃;The output of L-lactic acid using T11-1 and O7-7 from corncob respectively were 31.30g/L and 30.88g/L,and the conversion rate respectively were 52.17% and 51.47%.