A complete route for biodegradation of potentially carcinogenic cyanotoxin microcystin-LR in a novel indigenous bacterium

• Published in: Water research (Oxford) 2020-05, Vol.174, p.115638-115638, Article 115638
• Main Authors: Yang, Fei, Huang, Feiyu, Feng, Hai, Wei, Jia, Massey, Isaac Yaw, Liang, Geyu, Zhang, Fang, Yin, Lihong, Kacew, Sam, Zhang, Xian, Pu, Yuepu
• Format: Article
• Language: English
• Subjects: Biodegradation; Biodegradation, Environmental; Cyanobacterial blooms; Ecosystem; Microcystin-LR; Microcystins; Multi-omics analysis; Sphingomonadaceae; Sphingopyxis
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2020.115638

Microcystin-leucine-arginine (MC-LR), a cyclic potentially carcinogenic hepatotoxin, occurs frequently in aquatic habitats worldwide and seriously threatens ecosystem and public health. Limited effectiveness of physicochemical treatments to remove MC-LR from drinking water has led to a search for alternative cost-effective and environment friendly biodegradation strategies. Obtaining MC-degrading bacteria and understanding their MC-degrading mechanisms are outstanding challenges. Here, a novel indigenous bacterium named Sphingopyxis sp. YF1 with a high efficient capacity for MC-degradation was successfully isolated from eutrophic Lake Taihu. Through integrating mass spectrometer and multi-omics analyses accompanied by functional verification of certain genes and proteins, a complete MC-degradation pathway was firstly identified, in which MC-LR was sequentially degraded into linearized MC-LR, tetrapeptide, Adda, phenylacetic acid, and finally potential product CO2. Some specific proteins such as microcystinase, linearized-microcystinase, tetrapeptidease and PAAase responsible for this pathway were identified. This study pioneeringly demonstrated that MC-LR can be completely degraded through natural remediation processes and revealed a significant potential for MC-LR biodegradation in both natural environment and engineered systems. [Display omitted] •New MC-degrading genes and products were explored through a multi-omic approach.•A complete MC degradation pathway was identified.•A novel bacterium with high MC-degrading rate was isolated from Lake Taihu.•Proteomics data of MC-degrading bacteria were obtained for the first time.•A series of key enzymes responsible for detoxifying MC-LR were identified.