The Research Of ?-aminobutyric Acid Synthesized By Mold Transformation

?-aminobutyric acid(GABA),also known as 4-aminobutyric acid,The formula is C4H9NO2,relative molecular weight is 103.2,it is natural amino acid of non-protein composition and widespread in microbial,plant and animal cells.The molecular structure of GABA is unique,and it has special physiological effects and medicinal value,the market demand of GABA is also very gieat.Therefore,the preparation of its study has become a new hot spot.Microbial transformation is the use of glutamate dehydrogenase catalytic glutamic acid decarboxylation obtained GABA,with high utilization rate of glutamate,simple process,easy purification,shorter cycle and other advantages,the research is gradually rising.In this paper,taking mold strains our lab deposited as the original strain,screening by paper chromatograpHy,rescreening by TLC and berthelot colorimetry,MQ-9 was identified as the most excellent strain,GABA production reached 1.99 g / L,the molar conversion rate was 19.35%,MQ-9 was considered as the starting strain to do further research.GABA-high producing strain MQ-9 mutagenic treated by Ultraviolet-LiCl complex mutagenesis,glutamate transformation test results of mutagenesis strain were analyzed and compared,further determined that NW-3 is the best mutant,enzyme production medium of strain NW-3 was analyzed optimization by single factor and orthogonal experiment,the best composition of enzyme production medium is glucose 20 g / L,peptone 10 g / L,sodium succinate,6g / L,calcium chloride 5.5g / L,dipotassium hydrogen pHospHate 0.8g / L,calcium chloride 4g / L.Fermentation to produce the enzyme conditions of NW-3 was analyzed optimization on the basis of the best composition of enzyme production medium,optimal culture conditions were determined as fermentation temperature 31 ?,fermentation time 70 h,pH value 4.9,Inoculated seed age 18 h,inoculation 8%,rotation speed 170 r / min,based on the above optimum conditions,the GABA molar conversion rate of NW-3 is 32.03%,improved by 18 percentage points than unoptimized.optimizing immobilization and transformation Conditions of NW-3 thallus,optimal immobilization conditions is:formaldehyde concentration 0.5%,gelatin concentration 0.5%,the ratio of solids and liquids 1/6 m L·g-1,immobilization time 1.4h;The optimum conversion conditions of immobilized thallus is determined by single factor experiment and response surface analysis: transition temperature 41 ?,pH value 6.15,the conversion time 15.42 h,add thallus amount 8%,rotation speed 190 r / min,L-Glu concentration 0.15 mol / L,pH value of 6 acetate-sodium acetate buffer;Since the immobilized thallus that can indicate a certain extent reduced of GAD activity,it is very ideal that the strain NW-3 molar conversion rate achieved 34% under optimized conditions,continuous conversion stability test on immobilized thallus,after six consecutive conversions,enzyme activity retention rate is still more than 65%,immobilized thallu known to have better stability in continuous conversion;GABA content under optimal conversion conditions in the conversion solution is measured by high performance liquid chromatograp Hy,it can be further verified the feasibility of previous operation.