聚乙二醇水解菌PG-3的分离、鉴定及其水解酶特性研究

Isolation and identification of the PEG hydrolytic strain PG-3 and its enzymatic characteristics

从被聚乙二醇(PEG)长期污染的土壤中分离得到1株能够水解PEG但不能以PEG为唯一碳源生长的菌株PG-3,结合生理生化特征及16S rDNA基因序列同源性分析,将该菌株初步鉴定为Achromobacter sp.。LC-MS分析发现该菌株的代谢产物中出现了聚合度下降的聚乙二醇,表明其可能以水解的方式直接断裂PEG 1000中的醚键。菌株PG-3分泌的聚乙二醇水解酶(PEG-HD)为诱导酶,PEG 600～2000都能诱导其产生,其中PEG 1000诱导效果最佳;该酶最适反应温度为40℃,最适作用pH值为8.0,Cu2+、Zn2+对酶有抑制作用。PEG-HD的米氏常数(Km)为3.97 mmol.L-1,最大酶促反应速率(Vmax)为68.03μmol.mL-1.min-1。

A PEG-hydrolyzing bacterial strain PG-3 was isolated from long-term PEG-polluted soil, which was not able to utilize PEG as the sole carbon source for growth. Based on the analysis of its 16S rDNA gene sequence and its morphological, physiological and biochemical properties, strain PG-3 was identified as Achrornobacter sp.. Liquid chromatography mass spectrometry（LC-MS） analysis showed that strain PG-3 could directly depolymerize PEG 1000 by hydrolysis. PEG hydrolase（PEG-HD） produced by strain PG-3 was induced by PEG 600-2000, especially by PEG 1000;The optimum temperature of PEG-HD was 40 ℃, the optimum pH was 8.0, and Cu2＋ and Zn2＋ could inhibit enzyme activity. The Michaelis constant （ Km ） of PEG-HD was 3. 97 mmol.L-1 , with a maximum enzymatic reaction rate （ Vmax ） of 68. 03 μmol- mL-1. min-1.