Graham Emily B, Gabor Rachel S, Schooler Shon, McKnight Diane M, Nemergut Diana R, Knelman Joseph E
Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States of America.
School of Environment and Natural Resources, Ohio State University, Columbus, OH, United States of America.
PeerJ. 2018 Apr 3;6:e4575. doi: 10.7717/peerj.4575. eCollection 2018.
Recent advances have allowed for greater investigation into microbial regulation of mercury toxicity in the environment. In wetlands in particular, dissolved organic matter (DOM) may influence methylmercury (MeHg) production both through chemical interactions and through substrate effects on microbiomes. We conducted microcosm experiments in two disparate wetland environments (oligotrophic unvegetated and high-C vegetated sediments) to examine the impacts of plant leachate and inorganic mercury loadings (20 mg/L HgCl) on microbiomes and MeHg production in the St. Louis River Estuary. Our research reveals the greater relative capacity for mercury methylation in vegetated over unvegetated sediments. Further, our work shows how mercury cycling in oligotrophic unvegetated sediments may be susceptible to DOM inputs in the St. Louis River Estuary: unvegetated microcosms receiving leachate produced substantially more MeHg than unamended microcosms. We also demonstrate (1) changes in microbiome structure towards , (2) metagenomic shifts toward fermentation, and (3) degradation of complex DOM; all of which coincide with elevated net MeHg production in unvegetated microcosms receiving leachate. Together, our work shows the influence of wetland vegetation in controlling MeHg production in the Great Lakes region and provides evidence that this may be due to both enhanced microbial activity as well as differences in microbiome composition.
最近的进展使得对环境中汞毒性的微生物调控有了更深入的研究。特别是在湿地中,溶解有机物(DOM)可能通过化学相互作用以及对微生物群落的底物效应来影响甲基汞(MeHg)的产生。我们在两种截然不同的湿地环境(贫营养无植被和高碳有植被沉积物)中进行了微观实验,以研究植物渗滤液和无机汞负荷(20毫克/升HgCl)对圣路易斯河河口微生物群落和甲基汞产生的影响。我们的研究揭示了有植被沉积物中汞甲基化的相对能力比无植被沉积物更强。此外,我们的工作表明了圣路易斯河河口贫营养无植被沉积物中的汞循环可能如何受到DOM输入的影响:接受渗滤液的无植被微观环境产生的甲基汞比未添加渗滤液的微观环境多得多。我们还证明了(1)微生物群落结构向……的变化,(2)宏基因组向发酵的转变,以及(3)复杂DOM的降解;所有这些都与接受渗滤液的无植被微观环境中甲基汞净产量的增加相吻合。总之,我们的工作展示了湿地植被对五大湖地区甲基汞产生的控制作用,并提供了证据表明这可能是由于微生物活性增强以及微生物群落组成差异所致。