Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China.
Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, China.
Sci Total Environ. 2020 Mar 25;710:136401. doi: 10.1016/j.scitotenv.2019.136401. Epub 2020 Jan 3.
Over decades many studies have focused on the biodegradation of microcystins (MCs), and some Mlr-dependent MC-degrading bacteria were recorded, but the ecological functions, metabolic traits, and potential evolution of these organisms remain poorly understood. In this study, 16S rRNA-based phylogeny unraveled a wide range of genetic diversity across bacterial lineage, accompanied by re-evaluation of taxonomic placement of some MC-degrading species. Genome-wide comparison showed that considerable genes unique in individual organisms were identified, suggesting genetic differentiation among these Mlr-dependent MC-degrading bacteria. Notably, analyses of metabolic profiles first revealed the presence of functional genes involved in phenylacetate biodegradation in the specialized genomic regions, and mlr gene cluster was located around the neighborhood. The identification of transposable elements further indicated that these genomic regions might undergo horizontal gene transfer events to recruit novel functionalities, suggesting an adaptive force driving genome evolution of these organisms. In short, phylogenetic and genetic content analyses of Mlr-dependent MC-degraders shed light on their metabolic potential, ecological roles, and bacterial evolution, and expand the understanding of ecological status of MCs biodegradation.
几十年来，许多研究都集中在微囊藻毒素（MCs）的生物降解上，已经记录了一些依赖 Mlr 的 MC 降解细菌，但这些生物体的生态功能、代谢特征和潜在进化仍知之甚少。在这项研究中，基于 16S rRNA 的系统发育揭示了细菌谱系中广泛的遗传多样性，并重新评估了一些 MC 降解物种的分类地位。全基因组比较表明，在单个生物体中鉴定出了相当数量的独特基因，表明这些依赖 Mlr 的 MC 降解细菌之间存在遗传分化。值得注意的是，代谢谱分析首次揭示了在专门的基因组区域中存在参与苯乙酸生物降解的功能基因，而 mlr 基因簇位于附近。转座元件的鉴定进一步表明，这些基因组区域可能经历了水平基因转移事件，以招募新的功能，这表明一种适应性力量推动了这些生物体的基因组进化。简而言之，对依赖 Mlr 的 MC 降解菌的系统发育和遗传内容分析揭示了它们的代谢潜力、生态作用和细菌进化，并扩展了对 MCs 生物降解生态状况的理解。
