蜡状芽胞杆菌对芘的降解特性及降解酶研究

The biodegradation characteristics of Pyrene Bacillus cereus and its enzyme

考察蜡状芽胞杆菌(Bacillus cereus)对水体中芘的降解特性,分析其代谢产物和降解酶的活性.结果表明,1 mg·L-1Mn2+、0.1 mg·L-1Fe3+和10 mg·L-1葡萄糖混合物对芘的降解有明显促进作用;1 g·L-1菌体在120 h内对2.5μmol·L-1芘的降解率达到61.4%.利用LC-MS/MS分析芘代谢产物,检测到1-萘酚、2-萘酚、9-羟基菲和1-羟基芘4种单羟基多环芳烃,表明芘在单加氧酶作用下开环降解,且B.cereus能有效分解利用4种代谢产物,其最高利用率分别为100%、90.3%、98.3%和52.7%.酶活力分析实验结果表明,B.cereus具有的水杨酸羟化酶,邻苯二酚1,2-双加氧酶和邻苯二酚2,3-双加氧酶在芘的降解中起关键作用,其酶活力经芘诱导后均有明显提高.结合产物分析及酶活测定,推断B.cereus对芘的降解途径以及降解过程是由单加氧酶和双加氧酶联合起作用.

The characteristics and metabolites of pyrene degradation in water by Bacillus cereus and its enzyme activity were studied. The results show that pyrene degradation was promoted when mixing with Mn2 ＋,Fe3 ＋and glucose at the concentrations of 1 mg·L- 1,0. 1 mg·L- 1and 10 mg·L- 1,respectively. Within 120 hours,the degradation rate of 2. 5 μmol·L- 1pyrene by 1 g·L- 1biomass was 61. 4%. Four hydroxyl metabolites of pyrene,namely 1-naphthol,2-naphthol,9-phenanthrol and 1-pyrenol were detected by using LC-MS / MS,which suggestes that the ring-cleavage of pyrene was initiated by monooxygenase,and these four hydroxyl metabolites were utilized by B. cereus effectively. The utilization rates of theses metabolites were100%,90. 3%,98. 3% and 52. 7%,respectively. The results of enzyme activities analysis show that salicylate hydroxylase,catechol 1,2-dioxygenase and catechol 2,3-dioxygenase of B. cereus played a key role in degradation of pyrene,and the enzyme activities were obviously enhanced after pyrene treatment. Based on the product analysis and enzymatic determination,it was speculated that the degradation pathway of pyrene by B. cereus was due to the combined effects of monooxygenase and dioxygenase system.