Study On Lactobacillus Acidophilus Modificatin Of Surface Hydrophobic Space And Its Characteristics Of Catalyzed Conjugated Linoleic Acid To Linoleic Acid

Conjugated linoleic acid(CLA) is the isomers of linoleic acid(LA), which has important physiological functions. CLA can be obtained by Linoleic acid isomerase which converts LA to CLA. Lactobacillus acidophilus has high catalysis to ismerize LA to CLA. The CLA productivity is correlated to cell-surface hydrophobicity, permeability of cells and reaction system. In this paper, the correlation between cell-surface hydrophobicity and the activity of linoleic acid isomerase and the effects of different factors on the cell-surface hydrophobicity were studied. The effects of permeability treatment cells on the activity of linoleic acid isomerase were investigated. The reaction systems were screened and the reaction conditions were optimized.Lactobacillus acidophilus linoleic acid enzyme activity had been studied which were under the different hydrophobic environment,the results showed that La. surface hydrophobicity and its linoleic acid isomerase enzyme activity had a positive correlation, regression equation was:y=1.5500+78.163x. R2=0.7507specification model has higher fitting degree, significant analysis shows that P (0.003)<P (0.05), the results were significative, can be used as the response prediction. The medium component and cultivated conditions of La. for high hydrophobicity by single factor and response surface experiment,.Optimiz the hydrophobic rate conditions by using minitab16software analysis, the final determination of the bacteria conditions were:growth time of15.7h,4%glucose, peptone/yeast extract2:1, carbon nitrogen ratio2:1,0.4%of CH3COONa,0.15%of Ammonium citrate dibasic,0.181%of Twain-80(v/v), pH4,0phosphate buffer and bacterial suspension value of1.0×109cfu/mL. Hydrophobic rate increased by13.6%than before.Lactobacillus acidophilus were be cultivated under the optimal conditions of hydrophobic,and using the orthogonal design to optimize the permeability condition.The permeability conditions were25%aectone,processing time for40min, the processing temperature of40℃, the enzyme activity was as high as398.65U/g.The results were4.7times of crude enzyme liquid enzyme activity, the conversion rate was80.35%, increased by6.73%than before optimization.Selected a system of glycerol for higher CLA yield by single factor experiments, determined the best level of various factors of the system. Using the response surface method of biotransformation conditions optimization, using minitab16software analysis, finally improve the yield of CLA were the best reacting conditions:reacting temperature of36.5℃for23.7h, the substrate concentration was1.1mg/mL, cell concentration of4.0×109cfu/mL. Under the condition of the CLA concentration of8.422mg/mL.Over all, the yield of CLA was46.31%higher than normal cells,36.61%increase over the crude enzyme liquid.