Díaz-Torres Osiris, Lugo-Melchor Ofelia Yadira, de Anda José, Orozco-Nunnelly Danielle A, Gradilla-Hernández Misael Sebastián, Senés-Guerrero Carolina
Centro de Investigacion y Asistencia en Tecnologia y Diseño del Estado de Jalisco, A.C., Unidad de Servicios Analiticos y Metrologicos, Guadalajara, Mexico.
Departamento de Tecnologia Ambiental, Centro de Investigación y Asistencia en Tecnologia y Diseño del Estado de Jalisco, A.C, .Zapopan, Mexico.
Front Microbiol. 2022 Dec 2;13:1037626. doi: 10.3389/fmicb.2022.1037626. eCollection 2022.
Lake Cajititlán is a subtropical and endorheic lake, which is heavily impacted by nutrient pollution. Agricultural runoff and poorly treated wastewater have entered this reservoir at alarming rates during past rainy seasons, causing the cultural eutrophication of this body of water and resulting in several massive fish kill events. In this study, shotgun metagenomic sequencing was used to examine the taxonomic and functional structure of microbial communities in Lake Cajititlán during the rainy season. Several water quality features and their interactions with microbial communities were also assessed to identify the major factors affecting the water quality and biota, specifically fish species. According to current water quality regulations, most of the physicochemical variables analyzed (dissolved oxygen, pH, Secchi disk, NH , NO , blue-green algae, total phosphorus, and chlorophyll-) were outside of the permissible limits. and were the most abundant phytoplankton species, and the dominant bacterial genera were , , and , with , , and representing the most abundant bacterial species. All of these microorganisms have been reported to be potentially harmful to fish, and the latter three (, , ) also contain genes associated with pathogenicity in fish mortality (, S, , , , , , ). Genetic evidence from the microbial communities analyzed herein reveals that anthropogenic sources of nutrients in the lake altered genes involved in nitrogen, phosphorus, sulfur, and carbon metabolism, mainly at the beginning of the rainy season. These findings suggest that abiotic factors influence the structure of the microbial communities, along with the major biogeochemical cycles of Lake Cajititlán, resulting in temporal variations and an excess of microorganisms that can thrive in high-nutrient and low-oxygen environments. After reviewing the literature, this appears to be the first study that focuses on characterizing the water quality of a subtropical hypereutrophic lake through associations between physicochemical variables and shotgun metagenomic data. In addition, there are few studies that have coupled the metabolism of aquatic ecosystems with nutrient cycles.
卡希蒂特兰湖是一个亚热带内流湖，受到营养物质污染的严重影响。在过去的雨季，农业径流和处理不当的废水以惊人的速度进入这个水库，导致这片水体出现富营养化，引发了多起大规模鱼类死亡事件。在本研究中，采用鸟枪法宏基因组测序技术，对雨季期间卡希蒂特兰湖微生物群落的分类和功能结构进行了研究。同时还评估了若干水质特征及其与微生物群落的相互作用，以确定影响水质和生物群（特别是鱼类物种）的主要因素。根据现行水质法规，所分析的大多数理化变量（溶解氧、pH值、透明度、铵氮、硝氮、蓝藻、总磷和叶绿素）均超出了允许限值。蓝绿藻和硅藻是最丰富的浮游植物物种，优势细菌属为芽孢杆菌属、不动杆菌属和假单胞菌属，其中嗜麦芽窄食单胞菌、鲍曼不动杆菌和铜绿假单胞菌是最丰富的细菌物种。据报道，所有这些微生物都可能对鱼类有害，后三种（嗜麦芽窄食单胞菌、鲍曼不动杆菌、铜绿假单胞菌）还含有与鱼类死亡致病性相关的基因（flaA、S、rpoD、pilA、ompA、toxR、exoU）。本文分析的微生物群落的遗传证据表明，湖泊中营养物质的人为来源改变了参与氮、磷、硫和碳代谢的基因，主要发生在雨季开始时。这些发现表明，非生物因素影响着微生物群落的结构，以及卡希蒂特兰湖的主要生物地球化学循环，导致了时间上的变化以及大量能在高营养和低氧环境中繁衍生息的微生物。在查阅文献后发现，这似乎是第一项通过理化变量与鸟枪法宏基因组数据之间的关联来聚焦亚热带富营养化湖泊水质特征的研究。此外，很少有研究将水生生态系统的代谢与营养循环结合起来。
