Research On The Response System Of Bioconversion Of CLA By Lactobacillus Plantarum ZS2058

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid (C_18:2, cis-9, cis-12 octadecadienoic). CLA has potential health or nutritional effects, including anticarcenogenic activity, antiatherogenic activity, and the ability to reduce the catabolic effects of immune stimulation and to reduce body fat. Between the individual isomers of CLA, c-9,t11-CLA has been implicated as the most biologically active. As lactic acid bacteria bioconversion of CLA is safe and specificity, has been the focus of considerable research efforts in recent years.In this paper, through a combination of three detection methods of GC, Ag⁺-HPLC and GC-MS, determined the main products of bioconversion of CLA by resting cells of Lactobacillus plantarum ZS2058 were c9,t11-CLA, t10,c12-CLA and t,t-CLA.The most suitable detection method of the subject was GC.According to the production of CLA, bioconversion of CLA by resting cells of Lactobacillus plantarum ZS2058 in potassium phosphate buffer system was optimized by comparing with other reaction mediums of the organic medium, micro-water medium and two-phase medium.374μg/mL c9, t11-CLA was obtained under the reaction condition as follows: 0.8mg/mL LA solution, 4×10¹⁰cfu/mL cell mass, optimal temperature37℃and the optimal pH value 6.5. Conversion ratio of c9, t11-CLA was 46.75%.In this paper, effects of the substrate concentration, cell mass, reaction pH and reaction temperature on the early reaction speed of producing CLA by L.plantarum ZS2058 were discussed. The results showed that marked substrate inhibition was exist. When the LA concentration was 0.4 mg/mL, the early reaction speed of producing c9, t11-CLA reached the maximum value of 15.99μg/(mL·h). The early reaction speed ascended with the cell mass increasing. When the cell mass of 5×10¹⁰cfu/mL, the response rate close to the maximum value. The optimum pH and the optimum temperature of bioconversion of CLA were 6.5 and 40℃.Milosevic Parameters were obtained by double-reciprocal plot method and Hanes-Woolf plot method. The reaction rate equations of the initial response stage were established under different substrate concentration. The reaction rate equation follow the classic Milosevic equation at the low substrate concentration. Get the Milosevic Parameters was: Vmax: 21.74μg/(mL?h), Km: 0.16 mg/mL. Marked substrate inhibition was existed at the high substrate concentration. But our reaction rate equation of high substrate concentration was significant difference from the classic response rate equation of substrate inhibition. At last, the reaction rate equations were verified under different substrate concentration.