Screeming Of γ-aminobutyric Acid Produced Molds By Biotransformation And Optimizing Of Technology Conditions

γ-aminobutyric acid (GABA) is a functional and non-protein amino acid. Studieshave shown that γ-aminobutyric acid has high medicinal value and feed value. It has abroad market prospect. On the other hand, L-glutamate industry overcapacityincreasingly serious. Producing GABA from L-glutamic acid or glutamate not only hasenormous economic benefits but also possess the urgency. This paper produces GABAwith biotransformation. Experiment concertrates on the screening and identification ofthe GABA producing strain, the optimization of culture and biotransformation. Themain results are as follows:In this study,strain CQY-2with higher conversion and better specificity wasselected from38mold by repeated screening. The molar conversion rate of GABAreached19.20%. By morphological and18S rDNA sequence analysis, the strain wasdetermined as the Lichtheimia ramosa (horizontal stems mold), a kind of Absidia.Then Strain was mutated using UV Mutation Breeding obtained the mutant strainsLichtheimia ramosaUV2-14, the mutant was cultivated for a period of time, and theability of conversion was improved11.14%higher than the original strain. Also foundthat this strain retain the high conversion rateand high genetic stability after6pass-generation.The enzyme production medium composition of strain UV2-14optimized throughsingle factor and orthogonal experiments, results show that the optimized enzymeproduction medium: glucose20g/L, sodium succinate6g/L, peptone12g/L, calciumchloride7.5g/L, dipotassium hydrogenphosphate1.0g/L of L-glutamic acid3g/L,vitamin B60.2g/L.Culture conditions of Strain UV2-14for producing enzyme were optimized. Bysingle factor experiments，we found that optimal culture conditions for enzymeproduction: inoculation age and the inoculum size is12and8%, respectively.Initial pHis5.0~5.5, loading volume is60mL in each250ml shake flask.cultures were cultivatedwith160r/min and30℃, then they were collected After84h.Under these conditions,the mole conversion rate of L-glutamate to GABA reached29.11%with strain UV2-14,and1.36times higher than before.By Single factor experiment we explored the Process of conversion of L-glutamicacid to γ-aminobutyric acid process with Strain UV2-14, and optimal conditions of transformation were determined. Which the optimal conversion temperature and pH is40℃and5.0, respectively; acid-sodium acetate buffer was selected as optimal buffersystem; optimum substrate concentration is0.1mol/L and the optimum inoculumconcentration is6%; the optimum speed of shake flasks is200r/min. after12htransformation, production of γ-aminobutyric acid the and molar conversion ratereached3.79g/L and36.8%，respectively. under optimal conditions,The transformationof the culture is steady and the substrate glutamic acid is utilized except smalleramount of negative whereabouts （0.68g/L）, which can be accepted in the industry.Experimental results lay the foundation for the synthesis of GABA with industrialfungus.