假单胞菌F12转化DL-ATC产物的鉴定及转化条件的研究

Identification of bioconversion product from DL-ATC and optimization of reaction conditions in Pseudomonas sp. F12

目的:确定假单胞菌F12合成产物是否为L-半胱氨酸,减少生成的L-半胱氨酸的降解,增加转化DL-2-氨基-Δ2-噻唑啉-4-羧酸(DL-ATC)合成L-半胱氨酸的得率。方法:研究通过高效液相色谱和质谱分析确定产物;在不同反应条件下探索L-半胱氨酸降解情况,找到抑制脱巯基酶降解的因素。结果:通过与L-半胱氨酸标准品比较,液相色谱和质谱结果显示该菌的转化产物为L-半胱氨酸;隔绝空气下L-半胱氨酸降解产生的少量硫化氢对L-半胱氨酸的降解有很强的抑制作用,在此条件下转化DL-ATC合成L-半胱氨酸浓度最高达到46.2 mmol/L,得率由31.6%提高到94%。结论:菌株假单胞菌F12转化DL-ATC产物为L-半胱氨酸,隔绝空气条件下有利于L-半胱氨酸的积累。

Objective： To identify the bioconversion product from DL-2-amino-Δ^2-thiazoline-4-carboxylic acid（DL-ATC） and enhance L-cysteine yield from it. Methods： Reaction mixture was analyzed by HPLC and LCMS; comparison among different reaction conditions of L-cysteine decomposition were performed. Result： Contrast to standard L-cysteine, the results of HPLC and LC-MS indicated that it was L-cysteine; a small amount of hydrogen sulfide produced from degradation of L-cysteine inhibited L-cysteine desulfhydrase dramaticly in air-free condition which contribute the highest amount of L-cysteine arrived 46.2 mmol/L with a yield of 94%, in contrast to that of 31.6% under initial condition. Conclusion： Pseudomonas sp. F12 equipped with the ability of converting DL-ATC to L-cysteine; it was beneficial for L-cysteine accumulation in air-free condition.