School of Marine Science and Policy, University of Delaware, Lewes, DE, USA.
Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, USA.
Environ Microbiol Rep. 2020 Apr;12(2):195-202. doi: 10.1111/1758-2229.12823. Epub 2020 Feb 20.
Meromictic lakes are stratified lakes that typically stimulate phototrophic anoxic microbial metabolism, including the transformation of sulphur. Less studied are the transformations of mercury in these environments, and the microorganisms, which mediate these reactions. In order to further an understanding of redox species, mercury and microbial populations in meromictic lakes, we examined the geochemistry and microbiology of Glacier Lake in Jamesville, NY. We found an anoxic transition at a depth of 6 m, followed by active nitrate and sulphate utilization. A chlorophyll a maximum was located at 11 m, coinciding with peaks of several photoautotrophic microbial lineages and total mercury and methyl mercury. Via amplicon sequencing, the microbial population showed pronounced peaks of cyanobacteria at 10 m, Chlorobi at 12 m and Chloroflexi at 14 m. Sulphate-reducing bacteria were also most abundant between 10 and 14 m depth. A functional gene indicating the potential for the production of methyl mercury, hgcA, was detected at several depths in the lake. Our work suggests that in addition to the sulphur cycle, the cycling of mercury may be indirectly coupled with phototrophic processes in Glacier Lake.
分层湖是指那些通常会刺激光养缺氧微生物代谢的湖泊，包括硫的转化。这些环境中汞的转化以及介导这些反应的微生物则研究较少。为了进一步了解这些分层湖中的氧化还原物种、汞和微生物种群，我们研究了纽约州詹姆斯维尔的冰川湖。我们发现，在 6 米深处出现缺氧转变，随后硝酸盐和硫酸盐的利用变得活跃。叶绿素 a 的最大值位于 11 米处，与几个光自养微生物谱系以及总汞和甲基汞的峰值相对应。通过扩增子测序，微生物种群在 10 米处出现明显的蓝细菌高峰，在 12 米处出现绿弯菌高峰，在 14 米处出现绿屈挠菌高峰。硫酸盐还原菌在 10 到 14 米的深度也最为丰富。在湖中多个深度都检测到了一个功能基因 hgcA，该基因表明了生成甲基汞的潜力。我们的工作表明，除了硫循环外，汞的循环可能与冰川湖中光养过程间接耦合。
