Screening Of The Strain With High Yield Of γ-aminobutyric And Optimization Of Its Fermentation Conditions

γ-aminobutyric acid (γ-aminobutyric acid, GABA) is a kind of neural inhibitoryneurotransmitter, which can resist anxiety, reduce blood press, offer an stable nerve and enhancememory function. γ-aminobutyric acid is obtained mainly by chemical method and biologicalmethod. Chemical method is realized by adding a lot of chemical reagents, which increased theextraction difficulty and dangerousness. Thus, chemical method can not be used in food.Biological methods include plant enrichment method and microbial fermentation. Enrichmentmethod is the use of the plant having glutamic acid decarboxylase (Glutamic acid decarboxylase,GAD) which can convert glutamate to improve the GABA content. But in the drying process inthis method, sugar in plant itself can convert GABA to compound and can reduce the GABAyield. Therefore, obtaining GABA using microbial fermentation is worth to study. The study aimto screen a kind of food safety lactic acid bacteria with high GAD activity, then to mutate andfind its optimum fermentation conditions to improve the GABA production.1using selective medium (MRS) from sauerkraut, pickles and yogurt screened one strainwith high GABAproduction (145mg/L) was selected.2Mutation breeding were acted on strain to improve the GABA production and GABAproduction was improved after3times of mutation. Experiment results showed that strain has astable heredity and the GABA production was up to1.19g/L.3using orthogonality and response surface experiment design optimized strain medium andfermentation conditions. The results showed that glucose, yeast extract+rice bran, pyridoxalphosphate, L-glutamic acid in the medium had a significant effect on the growth of strain andyield of GABA, according to the four factors, four factors3levels orthogonal experiment wascarried out, the optimal combination of medium was glucose (10g/L), yeast extract+rice bran(1:1,20g/L), pyridoxal phosphate (2g/L), L-glutamate (10g/L). Using response surface analysisto optimize the fermentation conditions, the initial pH of fermented liquid was5.28,fermentation temperature and fermentation time was35.0℃and60h, respectively. The yield ofGABA is the largest at this time,3.16g/L.