摘要

      Lonar湖（印度）是一个高碱和高盐苏打湖，含有独特的微生物组成和功能。多年来，还没有利用全基因组测序技术对该生态系统进行分类多样性和功能方面的研究（重点是抗生素和金属抗性基因）。2013年、2016年和2018年的细菌多样性分析显示了变形菌门、硬壁菌门和拟杆菌门优势的差异。在古生物多样性方面，类似的模式持续存在，广古菌门具有较高的丰度。基因组分析表明，湖中存在抗药性基因（ARG）和金属抗性基因（MRG）谱。此外，还观察到一系列具有优势ARG类型的耐药基因，如多重耐药泵和β-内酰胺。湖水抗性基因中含有氟喹诺酮和吖啶酮抗性基因，表明湖水受到了污染。与抗有毒金属（砷、钴、镉、铜和锌）和阳离子流出蛋白CusA和抗钴锌镉蛋白相关的MRGs显示湖水受到了金属污染。这项研究可以作为一个基线去了解抗生素和金属抗性流行的机制源自于湖泊附近各种人为活动，并为珍稀的Lonar湖生态系统的保护找到综合途径。

      Lonar Lake (India) is a hyperalkaline and hypersaline soda lake encompassing unique microbial composition and functions. This ecosystem has not been explored for taxonomic diversity and functional aspects (with emphasis on antibiotic and metal resistance genes) using whole metagenome sequencing for multiple years. Bacterial diversity analysis during year 2013, 2016, and 2018 depicted differences in the dominance of Proteobacteria, Firmicutes and Bacteroidetes. For archaeal diversity, a similar pattern persisted with higher abundance of Euryarchaeota. Functional metagenome analyses, indicated presence of antibiotic resistance gene (ARG) and metal resistance gene (MRG) profiles in the lake. A wider continuum of resistance genes with dominant ARG types as multidrug resistance efflux pumps and beta-lactams were also observed. The lake resistome demonstrated fluoroquinolone and acriflavine resistance genes indicating sewage water contamination in the lake. The MRGs linked with resistance to toxic metals (arsenic, cobalt, cadmium, copper, and zinc) and cation efflux protein CusA and cobalt-zinc-cadmium resistance protein revealed metal contamination. This study could be a baseline for understanding prevalence of antibiotic and metal resistance mechanisms resulting from various anthropogenic activities nearby lake, and find integrated approaches for conservation of the precious Lonar Lake ecosystem.

      https://www.sciencedirect.com/science/article/abs/pii/S1470160X19308210