Study On Mutation And Breeding Of High-yield GABA Saccharomyces Cerevisiae And Optimization Of Its Fermentation Conditions

Gamma-aminobutyric acid(GABA) was an non-protein amino acid which existed widely in the body of vegetables and animals.It had many kinds of physiological functions such as stress response and resisting pathogen attack of plants,etc.GABA was the most important inhibitory transmitter in the central nervous system in animals.It played an important role in the physiological activities of the brain circulation,curing epilepsy and hypertension,calming,promoting sleep, enhancing memory,controlling asthma,regulating hormone secretion,promoting procreation,activating liver and kidney function,and so on.So it was widely used in food and medicine.Current research was focused on its action mechanism and its production.A large number of GABA products were produced by the fermentation of escherichia coli,but these products were unsafe.So it was very important that high-yield GABA and safe strain was breeded by mutagenicity.In this paper,the mutant was isolated from the populations of the Saccharomyces cerevisiae strain which was treated with 1mg/ml NTG in ten min.the GABA production in fermentation broth of mutant strain was determined by thin layer chromatography and spectrophotometry.In contrast with parent strain,the GABA production by the mutant was increased.Submerged culture showed that the hereditary character of the highly GABA-producing mutant 4 was stable.The fermentation conditions for GABA production by the mutant4 were tested in shaking-flask culture.Some factors such as carbon sources,nitrogen sources,inorganic salt,initial pH,cuture temperature and time,rotation speed,seed age,and so on, affected the production of GABA.The optimal culture media are:3%glutathione,3% peptone,0.3%(NH₄)₂SO₄,0.1%KH₂PO₄.The optimal fermentation conditions were as follows:initial pH 5.5,cuture temperature 30℃,rotation speed 220r/min,seed age 2d, inoculum size 4%and culture time 4d.In this condition,the yielding capacity of GABA by the mutant was 2.590g/l.