Studies On The Mutation And Optimization Of The Fermentation Conditions Of GABA-Producing Lactobacillus

The GABA ,is a kind of non-protein amino acid which widely both in the prokar- yotic creature and eukaryote.It is one of the most materials to transfer nerve informat- ion by restraining.It has various physiological functions to the human body ,having anti-out of gear rhythm of the heart to disorder function,having antihypertensive,the cardiovascular conditioning,calm nerves and improve physiological activity of role.Thus function as a new factor in the field of functional foods have broad application prospects.In this paper,GABA-producing strain breeding and fermentationg process were studied.A GABA-yielding strain B2 was isolated from the laboratory and identified as Lactobacillus brevis.It was shown the Lactobacillus brevis B2 had the ablity of producing GABA.Test results show that the production of lactic acid bacteria cells with the capacity of GABA,the initial capacity of 1.281g/L.Then,UV was used to treat the ablity of producing GABA.After several times of mutagenesis,a mutant strain B2 was bred by GABA resistance selection.Moreover,the GABA-producing capacity could be maintained stably after 8 generations.Comparison of this characters,sTab. genetic traits,the fermentation results indicated that the average yield of GABA was 3.58g/L.Mutation of the fermentation conditions of single-factor test to determine the best medium for the initial pH 7.0, fermentation temperature is 33℃, 3d fermentation time. The effects of 6 major culture components,defatted soybean flour, Lmono-sodium glutamate(L-MSG),corn steep liquor powder (CSLP),glucose, K₂PHO₄ and yeast of final results were DSE,CSLP and L-MSG,respectively. Take this three factors as independent variable,GABA output is to respond to value , design that with Box-Behnken,build the return model producing GABA bacterium kind of culture medium staple three factors bean cake powder ,maize thick fluid powder ,L-MSG ,analyse the inside law optimizing culture medium product GABA, reach three factors being bean cake powder , maize thick fluid powder , L-MSG in proper order to the effect size producing GABA. The best to theory verifies through, produces condition reaching the best culture medium for the soymeal being degrease turns to powder with a view of reality 17.98g/L, maize thick fluid powder 21.73g/L, produces GABA contents after L-MSG13.67g/L, the culture medium optimization being 5.3g/L. Repetitiveness test result is fairly good, certificate that method is feasible,reaches design demand.Pilot third was carried out in 25L bioreactor to demonstrate the result of optimization of fermentation conditions.Queen who expands the scale fermentation, GABA output is 4.2g/L about.The optimization of fermentation conditions can be-amplified and the main content of GABA fermentation broth was lactic acid 5.77mg/L,protein 10.87mg/L,glucose 0.3mg/L, glutamic acid 2.3mg/L,GABA 4.2mg/L.