Zhu Congmin, Zhang Junyi, Wang Xin, Yang Yuqing, Chen Ning, Lu Zuhong, Ge Qinyu, Jiang Rui, Zhang Xuegong, Yang Yunfeng, Chen Ting
Institute for Artificial Intelligence and Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China.
State Key Lab for Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China; Wuxi Environmental Monitoring Centre, Wuxi, China.
Water Res. 2021 May 15;196:117014. doi: 10.1016/j.watres.2021.117014. Epub 2021 Mar 7.
Freshwater lakes are threatened by harmful cyanobacterial blooms, whose basic unit is Cyanobacterial Aggregate (CA). CA-attached bacteria play a significant role through different blooming stages with substantial variation of their taxonomic structure. However, little is known about their functional variations and functional links with cyanobacteria due to the lack of reference genomes. In this longitudinal study, we collected 16 CA samples from Lake Taihu, one of China's largest freshwater lakes, from April 2015 to February 2016, and sequenced their V4 region of 16S rRNA genes, full metagenomes (MG), and metatranscriptomes (MT). The analysis of these data revealed the dynamics of microbial taxonomic and functional structure in CAs, influenced by both external environmental factors and internal metabolism. 55 OTUs, 456 genes, and 37 transcripts showed significantly differential abundance across the early, middle, and late blooming stages (ANOVA test, P < 0.05). Total nitrogen and total phosphorus were proved to be the most important environmental drivers of microbial taxonomic and functional variations in CAs (Mantel's r > 0.25, P < 0.05). We constructed 161 high-quality metagenome-assembled genomes (MAGs), out of which 22 were cyanobacterial strains with diverse energy pathways, transporters and prokaryotic defense systems. Based on these MAGs, we constructed a cyanobacteria-bacteria co-nitrogen-pathway and a cyanobacteria-bacteria co-phosphorus-pathway, by which we demonstrated how nitrogen and phosphorus influence the dynamics of the microbial structure to a certain extent by affecting these co-pathways. Overall, these results characterized the taxonomic, functional, and transcriptional variations of microbes in CAs through different blooming stages. Genome assembly and metabolic analysis of cyanobacteria and their attached bacteria suggested that the material exchange and signal transduction do, indeed, exist among them. Our understanding of the underlying molecular pathways for cyanobacterial blooms could lead to the control of blooms by interventional strategies to disrupt critical microbes' expression.
淡水湖泊正受到有害蓝藻水华的威胁，其基本单位是蓝藻聚集体（CA）。附着在CA上的细菌在不同的水华阶段发挥着重要作用，其分类结构存在显著差异。然而，由于缺乏参考基因组，人们对它们的功能变化以及与蓝藻的功能联系知之甚少。在这项纵向研究中，我们于2015年4月至2016年2月从中国最大的淡水湖之一太湖采集了16个CA样本，并对其16S rRNA基因的V4区域、全宏基因组（MG）和宏转录组（MT）进行了测序。对这些数据的分析揭示了CA中微生物分类和功能结构的动态变化，这受到外部环境因素和内部代谢的影响。55个操作分类单元（OTU）、456个基因和37个转录本在水华的早期、中期和晚期阶段显示出显著的丰度差异（方差分析测试，P < 0.05）。总氮和总磷被证明是CA中微生物分类和功能变化的最重要环境驱动因素（Mantel's r > 0.25，P < 0.05）。我们构建了161个高质量的宏基因组组装基因组（MAG），其中22个是具有不同能量途径、转运蛋白和原核防御系统的蓝藻菌株。基于这些MAG，我们构建了一个蓝藻 - 细菌共氮途径和一个蓝藻 - 细菌共磷途径，通过这些途径我们证明了氮和磷如何通过影响这些共途径在一定程度上影响微生物结构的动态变化。总体而言，这些结果表征了CA中微生物在不同水华阶段的分类、功能和转录变化。蓝藻及其附着细菌的基因组组装和代谢分析表明，它们之间确实存在物质交换和信号转导。我们对蓝藻水华潜在分子途径的理解可能会通过干预策略来破坏关键微生物的表达从而实现对水华的控制。
