Studies On Screening And Identification Of Lactic Acid Bacteria Producing CLA And The Enzyme Kinetics Of LAI

The test studies on how to develop a Lactic acid bacteria with health care function from fermented Chinese cabbage Juice. The strain was isolated by traditional laboratory methods and was preliminarily identified by the Gram stain. The 16S rDNA domain sequence was amplified by PCR, then PCR procucts were ligated into the T vector. After transformation, sequence analysiss and strain Species Identification were carried out. The results show that the strain is Lactobacillus coryniformis subsp. torquens strain 30. The production of conjugated linoleic acid is 0.0107mg/ml by UV analysis, and the conversion rate of conjugated linoleic acid is 2.51%.Firstly, Linoleate isomerase of Lactobacillus coryniformis were isolated and purified by 50% saturated ammonium sulfate, the recovery rate is 65.57% and the purification fold is 1.15, then it was isolated and purified by 80% saturated ammonium sulfate, the recovery rate is 44.62% and The purification fold is 3.73. Finally, the recovery rate is 10.32% and the purification fold is 8.36 by Sephadex G-100 gel filtration chromatography.The factors of culture temperature, culture time, pH, and inoculum of Lactobacillus coryniformis were researched by single factor experiment. The optimum parameters for production of CLA was determined: temperature 36℃, time 36h, pH5.0, inoculum4%. By Four factors and three level Orthogonal optimal design, the optimal parameters for production of CLA by Lactobacillus coryniformis was confirmed: incubation time 42h, temperature40℃, initial pH 5.0, inoculum4%.The production of conjugated linoleic acid is 0.00375mg/ml, and the conversion rate of conjugated linoleic acid is 8.8% under the optimal conditions. The conversion rate of substrate and the obtain rate of product are further improved. The result can lay basis for further application of lactic acid bacteria in health food, medicine and industry.