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A novel pathway for the anaerobic biotransformation of microcystin-LR using enrichment cultures

Zhu, Fan-Ping, Han, Zhen-Lian, Duan, Jian-Lu, Shi, Xiao-Shuang, Wang, Ting-Ting, Sheng, Guo-Ping, Wang, Shu-Guang, Yuan, Xian-Zheng
Environmental pollution 2019 v.247 pp. 1064-1070
anaerobic conditions, arginine, biodegradation, biotransformation, ecosystems, eutrophication, human health, lakes, microbial communities, microcystin-LR, sediments
Microcystin (MC) elimination is a global challenge that is necessary for the health of humans and ecosystems. Biodegradation of MC, one of the most environmental-friendly methods, had previously been focused on the aerobic condition. In this study, two enrichment cultures from Taihu sediments possessed high capacity for MC-leucine arginine (MC-LR) anaerobic biodegradation. Meanwhile, it was firstly found that MC-LR underwent similar degradation process under anaerobic conditions to that in aerobic condition. Furthermore, a novel degradation pathway, hydrolyzing of Ala-Mdha to form a new linear MC-LR intermediate, was proposed under anaerobic conditions. Combining MC-LR degradation with microbial community analysis, this study deduced that Candidatus Cloacamonas acidaminovorans str. Evry may play an important role in the degradation of MC-LR. These findings suggest an additional pathway involved in the environmental cycle of MC-LR, which implies that the biotransformation of MC-LR might play an important role in eliminating MC-LR in eutrophic lake sediments under anaerobic conditions.