摘要
筛选到一株能降解腈类化合物的暗灰链霉菌(Streptomyces canus)CGMCC 13662,该菌的生长细胞能在120 h内完全降解0.5 g·L-1苯甲腈,而其静息细胞仅需24 h就能完全降解苯甲腈。生长细胞只能将苯甲腈代谢为苯甲酰胺,而静息细胞还能继续将苯甲酰胺代谢为苯甲酸并进一步降解。暗灰链霉菌CGMCC 13662能同时降解苯甲酸代谢的中间产物儿茶酚和原儿茶酸,表明该菌株代谢苯甲酸主要通过儿茶酚和原儿茶酸途径。CoCl2诱导的菌体在苯甲腈代谢的前8 h内产生苯甲酸的量比无CoCl2诱导时低6倍,CoCl2可改变苯甲腈代谢流。苯甲腈的降解速率在酸性条件下降低,而苯甲酰胺的降解对pH值变化敏感,仅在pH值为7.5时达到最高。添加苹果酸盐后苯甲腈的降解半衰期由5.4减少到3.8 h,是转化苯甲腈的最适共代谢基质。葡萄糖和蔗糖对苯甲腈降解没有影响,但能抑制苯甲酰胺的进一步降解。该研究可为消除环境中苯甲腈及其中间代谢污染物以及探究苯甲腈代谢机制提供理论依据。
The nitrile-degrading actinomycetes Streptomyces canus CGMCC 13662 was used to study the degradation of benzonitrile and benzoic acid. Growing S. canus cells degraded 0.5 g·L-1 benzonitrile completely within 120 h, with the final metabolite being benzamide;the resting cells could completely degrade benzonitrile within 24 h and benzamide and benzoic acid were no longer present by the end of the assay. The actinomycetes simultaneously degraded catechol and protocatechuic acid, indicating that the metabolic pathway of benzoic acid was via the catechol and protocatechuic acid pathway. The amount of benzoic acid produced by CoCl2-induced actinomycetes after 8 h of benzonitrile metabolism was 6-fold lower than the control without cobalt, which indicated that benzonitrile degraded via the NHase/amidase and nitrilase pathways and CoCl2 could regulate the benzonitrile metabolic flux between them. The degradation rate of benzonitrile decreased under acidic conditions, while benzamide degradation was sensitive to the pH of the resting cell solutions and the maximum benzamide degradation was at pH 7.5. Malate was the optimal co-substrate for benzonitrile degradation, leading to a decrease in the half-life of benzonitrile degradation from 5.40 to 3.80 h compared with degradation without the co-substrate. Glucose and sucrose had no effect on benzonitrile degradation as co-substrates, while they inhibited the further degradation of benzamide. This study provides a theoretical basis for eliminating residues of benzonitrile and intermediate metabolic pollutants in the environment and exploring the metabolic mechanism of benzonitrile.
作者
郭铃
方文婉
葛峰
戴亦军
GUO Ling;FANG Wen-wan;GE Feng;DAI Yi-jun(College of Life Science/Jiangsu Key Laboratory for Microbes and Func tional Genomics/Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources,Nanjing Normal University,Nanjing 210023,China;Nanjing Institute of Environmental Sciences,Ministry of Ecology and Environment,Nanjing 210042,China)
出处
《生态与农村环境学报》
CAS
CSCD
北大核心
2020年第2期257-264,共8页
Journal of Ecology and Rural Environment
基金
国家自然科学基金(31570104)
关键词
暗灰链霉菌
苯甲腈
苯甲酸
微生物降解
Streptomyces canus
benzonitrile
benzoic acid
microbial degradation
