Study On The Fermentation And Application Of Lactic Acid Bacteria Producingγ-Aminobutyric Acid

GABA-producing strains were screened by paper chromatography and high performance liquid chromatography method. The strain was screened from pickles, showing the highest GABA-producing ability of1.261g/L. The strain was named as Lactobacillus plantarum WZ011via morphology observation,16S rDNA analysis and phylogenetic tree. Fermentation medium was optimized using single factor test and orthogonal design method. The optimal medium composition was as follows(g/L):glucose13, yeast5, monosodium glutamate12, C8H11NO3-HCl0.15, CH3COONa2, MgSO4·7H2O0.02, MnSO4·4H2O0.001, FeSO4·7H2O0.001, NaCl0.001. It was concluded from the curve of the fermentation kinetics that GABA fermentation process included two stages:cell growth and product formation. When the nitrogen source was abundant, the utilization rate of monosodium glutamate by Lactobacillus plantarum WZ011was low. When nitrogen source was decreased and C8H11NO3·HCl was added, the utilization rate of monosodium glutamate rose to99%and GABA production rate was increased more than twice. Under the optimum condition, the highest GABA production reached5.814g/L, which was79%higher than that in original fermentation condition. Furthermore, the duration of reaching the sationary phase of GABA production was decreased48h compared to the original fermentation conditions.The results showed that the optimal fermentation condition for GABA production was inoculum size4%, pH6.0, temperature35℃and stationary cultivation. The yield of GABA reached5.66g/L under the condition after120h, which was9.1%higher than that in original fermentation condition. The GABA production after optimization is the highest in the fermentation field in China.The further study on the application of Lactobacillus plantarum WZ011producing y-aminobutyric acid in orange juice fermentation implied that glucose concentration was the main factor on GABA producing. The optimal orange juice fermentation medium composition was as follows(g/L):diluted8times, yeast20, CH3COONa2, monosodium glutamate15. Under the optimum condition at35℃, the GABA production reached6.927g/L after120h stationary fermentation, which was22.4%higher than that in medium without orange juice. The number of viable Lactobacillus plantarum WZ011in the orange juice had reached5×107cfu/ml after fermentation.