克雷伯氏菌对三苯基锡的酶促降解特性

Characteristics of Biodegradation of Triphenyltin by Enzyme Obtained from Klebsiella pneumoniae

研究了肺炎克雷伯氏菌对三苯基锡(TPhT)的酶促降解性能,并对酶促反应影响因素的作用机制进行了探讨,以期为阐明有机锡的微生物降解机制提供实验依据.研究证明,菌体、分泌物和胞内降解酶均具有降解TPhT的能力,在30℃转速为130.rm in-1的摇床中避光处理2 h后,对3 mg.L-1TPhT的降解率分别为10.9%、5.3%和47.9%.影响因素实验表明,降解介质、pH、温度、TPhT浓度和金属离子均会对TPhT的酶促降解效果产生影响,其中TPhT酶促反应的最适pH和温度分别为8和50℃.Mg2+、Mn2+、Fe2+和Fe3+在合适的浓度范围内,均会促进TPhT的降解.当Mg2+的浓度为15 mg.L-1时,胞内酶对TPhT的降解率高达73.8%.金属离子的促进效果主要与其对酶的激活、作为电子受体或电子供体参与TPhT酶促降解等作用有关.TPhT的降解速率与其浓度呈现理想的线性关系.该反应的Vm ax和Km分别为0.15 mg.(L.m in)-1和47.1 mg.L-1.

The objective of this study is to illuminate the mechanism of biodegradation of triphenyhin （TPhT）. The removal of TPhT by Klebsiella pneumoniae was, therefore, investigated through characteristics studies. The influences of the various parameters were also discussed. The results demonstrated that the cell, extracellular secretion and intracellular enzyme were the effective biomasses for the biodegradation of TPhT. At initial concentration of 3 mg· L^-1, 10. 9%, 5.3% and 47.9% of TPhT could be degraded by these biomasses respectively at 30℃ within 2 hours under an rotary shaker at 120 r · min^-1. The experimental results also showed that the enzyme activity could be affected by the buffers, pH, temperature, metals and the concentration of TPhT. The degradation efficiency would reach the highest point at pH 8, and at the optimal temperature of 50℃. Metals including Mg^2＋, Mn^2＋, Fe^2＋ and Fe^2＋ improved the enzyme activity at certain concentrations. In the presence of 15 mg · L^-1 of Mg^2＋ , the removal percentage of TPhT was up to 73.8%. It suggested that the metals activated the enzyme and interacted with the TPhT enabling its removal during the biodegradation process. Linear plots of removal ratios versus concentrations of TPhT meant that the biodegradation fitted the MichaelisMenten model. The VmAx and K of this biodegradation were 0.15 mg · （L · min） ^-1 and 47. 1 mg · L^-1 , respectively.