Screening,Identification,UV Mutagenesis And Fermentation Conditions Optimization Of ?-aminobutyric Acid By Lactobacillus

?-Aminobutyric Acid is not only a non-protein amino acid that exists in nature,but also an important neurotransmitter in the human central nervous system.It is also a neuroinhibitory amino acid which can make blood pressure lower,improve and treat diabetes,treat epilepsy,fight against cancer and so on.The body's own ability to accumulate GABA gradually weakens with age,and supplementing from the daily diet can effectively improve this situation.Therefore,it is particularly important to study functional foods rich in GABA.In this paper,high-performance liquid chromatography was used to proceed Screening,Identification,UV Mutagenesis and Fermentation Conditions Optimization for GABA-producing lactobacillus strains in koumiss sample,in order to provide theoretical basis for the future industrial production of GABA.The main test results are as follows:1.The lactic acid bacteria isolated from the koumiss sample was used as the experimental strain.A strain of Lactobacillus with GABA-producing lactobacillus content of 0.731g/L was screened by high performance liquid chromatography(HPLC)and numbered 43.Strain 43 was identified as Lactobacillus plantarum by sugar fermentation experiment and 16 S rDNA gene sequence analysis.2.Using strain 43 as a starting strain,UV mutagenesis was studied.A mutant strain 43-7with a higher GABA yield was finally obtained through mutagenesis.The GABA production was 1.05g/L,GABA production was 43.6% higher than the original strain,and its stability was better after 10 passages.3.The comparison of Glutamate Decarboxylase(GADs)gene between strain 43 and mutant strain UV43-7 showed that the similarity of GAD gene before and after mutagenesis was 100% and the increase of UV43-7 production was not directly related to GAD genome.4.Through single factor experiment and response surface experiment,the optimal fermentation medium for GABA-producing strain UV43-7 was determined as follows:yeast powder 8.6g/L,glucose 11.2g/L,L-MSG 15g/L,peptone 5g/L,anhydrous sodium acetate 2g/L,magnesium sulfate 0.2g/L,ferrous sulfate 1mg/L,manganese sulfate 1mg/L;The optimum fermentation conditions were as follows: pH7.9,inoculation quantity 2.4%,cultivation temperature 36?,cultivation time 4d.The GABA yield of strain UV43-7 was4.003g/L under the optimum fermentation conditions.The results of this experiment provide reference significance for the fermentation of strain UV43-7 and GABA producing.