氯苯类化合物的生物降解

氯苯类生物降解机制可分为三类:氧化脱氯、还原脱氯和共代谢.氯苯类的氯化脱氯机制基本遵循一个相似的降解途径,即首先在双氯化酶攻击下形成二醇,此二醇脱氢形成氯代邻二酚.邻二酚开环产物是相应的氯化粘康酸,脱氯过程发生在此粘康酸内酯化过程中和内酯开环后;还原脱氯需要多种微生物共同参与,脱氯途径很不一样,这与不同微生物种群和不同的环境条件有关;共代谢作用降低了氯苯类化合物的生物毒性,使其更易为别的微生物同化.

BIODEGRADATION OF CHLOROBENZENES(CBS)--A REVIEW

Chlorinated Benzenes (CBs) are widely used industrial chemicals. In aerobic and anaerobic conditions, biodegradations of CBs by microorganisms were reviewed. The machanisms of biodegradation of CBs can be categorized as oxidative dechlorination, reductive dechlorination and cometablism. In oxidative dechlorinationn, CBs were biodegraded via a similar pathway. The initial oxidative attack by CBs dioxygenase is proceed via the chlorinated dihydrodiol, which should yield corresponding chlorocatechol upon enzymatic dehydrogenation and rearomatization. It follows a modified ortho cleavage pathway, yielding chloromuconic acid. The eliminating of chloride in the form of HCl occurs during the course of lactonization of the muconic acid, and after the cleavage of the lacton to form corresponding maleylacetate. In reductive dechlorination, the biodegradation pathways vary with different microbial consortium and environmental conditions. Cometablism reduces the toxicity of CBs, thus makes them more readily degraded by other microorganisms.