Frank Kiana L, Rogers Karyn L, Rogers Daniel R, Johnston David T, Girguis Peter R
Department of Molecular Biology, Harvard UniversityCambridge, MA, USA; Department of Oceanography, University of HawaiiHonolulu, HI, USA.
Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute Troy, NY, USA.
Front Microbiol. 2015 Dec 22;6:1449. doi: 10.3389/fmicb.2015.01449. eCollection 2015.
Hydrothermal vents are thermally and geochemically dynamic habitats, and the organisms therein are subject to steep gradients in temperature and chemistry. To date, the influence of these environmental dynamics on microbial sulfate reduction has not been well constrained. Here, via multivariate experiments, we evaluate the effects of key environmental variables (temperature, pH, H2S, [Formula: see text], DOC) on sulfate reduction rates and metabolic energy yields in material recovered from a hydrothermal flange from the Grotto edifice in the Main Endeavor Field, Juan de Fuca Ridge. Sulfate reduction was measured in batch reactions across a range of physico-chemical conditions. Temperature and pH were the strongest stimuli, and maximum sulfate reduction rates were observed at 50°C and pH 6, suggesting that the in situ community of sulfate-reducing organisms in Grotto flanges may be most active in a slightly acidic and moderate thermal/chemical regime. At pH 4, sulfate reduction rates increased with sulfide concentrations most likely due to the mitigation of metal toxicity. While substrate concentrations also influenced sulfate reduction rates, energy-rich conditions muted the effect of metabolic energetics on sulfate reduction rates. We posit that variability in sulfate reduction rates reflect the response of the active microbial consortia to environmental constraints on in situ microbial physiology, toxicity, and the type and extent of energy limitation. These experiments help to constrain models of the spatial contribution of heterotrophic sulfate reduction within the complex gradients inherent to seafloor hydrothermal deposits.
热液喷口是热动力学和地球化学动态的栖息地，其中的生物面临着温度和化学物质的陡峭梯度变化。迄今为止，这些环境动态对微生物硫酸盐还原作用的影响尚未得到很好的界定。在此，我们通过多变量实验，评估了关键环境变量（温度、pH值、硫化氢、[公式：见原文]、溶解有机碳）对从胡安·德富卡海岭主努力场石窟大厦热液法兰回收的物质中硫酸盐还原率和代谢能量产量的影响。在一系列物理化学条件下的分批反应中测量硫酸盐还原率。温度和pH值是最强刺激因素，在50°C和pH值为6时观察到最大硫酸盐还原率，这表明石窟法兰中硫酸盐还原生物群落的原位可能在微酸性和中等热/化学环境中最为活跃。在pH值为4时，硫酸盐还原率随硫化物浓度增加，这很可能是由于金属毒性的减轻。虽然底物浓度也影响硫酸盐还原率，但能量丰富的条件减弱了代谢能量学对硫酸盐还原率的影响。我们认为，硫酸盐还原率的变化反映了活跃微生物群落对原位微生物生理学、毒性以及能量限制类型和程度的环境限制的响应。这些实验有助于限制海底热液沉积物固有复杂梯度中异养硫酸盐还原的空间贡献模型。
