Screening And Identification Of Strains For Producing γ-aminobutyric Acid

GABA is a nonprotein natural amino acid,obtained by transformation of L-glutamic acid that is catalyzed by glutamate decarboxylase.γ-aminobutyric acid widely exists in nature,it’s putative inhibitory neurotransmitter of mammalian central nervous system,and has important physiological functions.It has great potential in the application of medical,food,health care,chemical and agriculture.The natural content of GABA is very low,and it’s very difficult to extract from plants and animals.At present,microbial fermentation is the best way to get GABA because of the advantages:mild,safety and low cost.The enzymatic activity of GAD that was reported is not particularly high,and the GABA yield is mostly around 3-30 mg/mL.The research objects are mostly about E.coli,there are huge safety hidden danger in the process of GABA biosynthesis,so the product has great limitation in the application of food and medicine.In recent years there have many studies on screening of GABA producing strains,but few can actually put into production.It’s still an urgent task to explore the safety and high-yield strain.In order to obtain safely strains for producing γ-aminobutyric acid,the strains were screened from pickled cabbage juice and yogurt,then preliminary analysis of the fermentation liquor was processed by thin layer chromatography(TLC),they were carried on the 16 S rDNA gene sequencing and GenBank comparing,finally,the high performance liquid chromatography(HPLC)method was used for quantitative analysis of γ-aminobutyric acid.Six γ-aminobutyric acid producing strains were screened from the liquid,The TLC results showed that those six strains were able to produce γ-aminobutyric acid,16 S rDNA gene sequencing and GenBank comparing results showed that six strains were identified to be short lactic acid bacteria.The yield of strains were among 200~500 μg/mL,while the maximum yield was 493.3 μg/mL.Silica gel thin-layer chromatography(THC)can rapid qualitative detect whether the γ-aminobutyric acid were contained in cultures,and the optimized HPLC method can accurately and quantitatively detected the content of γ-aminobutyric acid in cultures.The biological safety of those lactic acid bacteria were high,have certain application prospect.