碘普罗胺降解菌Pseudomonas sp. I-24共代谢降解性能研究

菌株Pseudomonas sp.I-24(I-24)难以利用碘普罗胺(IOP)作为唯一的碳源和能源进行生长和代谢,因此本研究选用淀粉、麦芽糖、葡萄糖和甘油作为I-24共代谢IOP的外加碳源,考察了在摇瓶实验中,不同外加碳源对I-24生长及降解IOP的影响.结果表明,I-24共代谢IOP符合一级反应动力学特征,淀粉对共代谢过程的促进作用最为显著,IOP的五日降解率可达到92.7%,I-24的IOP降解酶活力在培养第3 d达到最高0.182 mU,淀粉投加的最佳浓度为1 g·L-1,然而葡萄糖和麦芽糖分别对I-24的生长和电子传递系统活性(ETSA)有着最佳促进作用,表明降解菌生长过快将导致竞争性抑制,降低IOP降解率,同时ETSA与共代谢作用无直接关联.此外,从空白样表现出的酶活力得出IOP降解酶即使在低基质条件下同样可被诱导产生.

Study on the Iopromide-Degrading Characteristics of Strain Pseudomonas sp. I-24 via Co-Metabolism

Strain Pseudomonas sp. I-24 (I-24) cannot utilize iopromide (IOP) as the sole carbon and energy source, so different carbon sources (starch, malt sugar, glucose and glycerol) were used as the additional carbon sources to study their effects on I-24 growth and IOP degradation in flask tests. The results showed that the IOP degradation process by I-24 matched the first-order kinetics. Among these four co-substrates, starch was found to be the most efficient to enhance IOP degradation. The corresponding degradation efficiency was as high as 92.7% and the highest enzymatic activity of 0.182 mU appeared in the third day. The optimum starch concentration was 1 g·L^-1. Since glucose and malt sugar better promoted I-24 growth and electron transport system activity (ETSA), indicating that the IOP degradation process would probably be restrained by excess growth, which decreased the degradation efficiency of IOP. In addition, no direct correlation between ETSA and co-metabolism process was found. The detected enzymatic activity of I-24 in control sample indicated that the key enzymes could be still induced in low-concentration of co-substrates.