Relative importance of H2 and H2S as energy sources for primary production in geothermal springs
Relative importance of H2 and H2S as energy sources for primary production in geothermal springs
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DOI：
10.1128/aem.00852-08
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发表时间：
2008-09-01
影响因子：
4.4
通讯作者：
McDermott, Timothy R.
中科院分区：
文献类型：
--
作者：
D'Imperio, Seth;Lehr, Corinne R.;McDermott, Timothy R.
锗沃茨含有许多潜在的电子供体，能够支持以化能无机营养为基础的初级生产。在这样的系统中，特定的电子供体和受体对的能量产率的热力学预测是可用的，虽然这些预测的直接评估是罕见的。本研究评估的相对重要性，溶解的H-2和H2S作为能源的支持化能无机营养代谢的酸性地热泉在黄石国家公园。在流出通道中观察到H2S和H-2浓度梯度，并且在微生物垫内明显存在垂直H2S和O-2梯度。H2S水平和微生物消耗率比H-2高约三个数量级。氢杆菌样生物体占主导地位的微生物群落的细菌组分，和代表三个不同的16 S rRNA基因的基因型（EST-type = 100%的身份）的分离株进行了分离和表征。在一个菌型中，O-2的需求量不同，能源利用也不同：一些菌株只能用H2S生长，一些只能用H-2生长，而另一些菌株可以利用任何一种能源。这些代谢表型是一致的，在原位地球化学条件下测量水化学分析和现场测量，通过使用气相色谱法和微电极。对可以利用H2S和H-2并代表优势系统型（70%的PCR克隆）的分离株进行的纯培养实验表明，H2S和H-2同时使用，没有诱导或分解代谢物抑制的证据，并且相对速率差异与非原位现场测定的结果相当。在原位相关浓度下，该菌株在H2S中的生长优于在H-2中的生长。从这项研究中得出的主要结论是，生育可能不一定是可靠的预测生理和H2S可以支配H-2作为能源的可用性，明显的原位消费率，和生长支持能源。
Geothermal waters contain numerous potential electron donors capable of supporting chemolithotrophy-based primary production. Thermodynamic predictions of energy yields for specific electron donor and acceptor pairs in such systems are available, although direct assessments of these predictions are rare. This study assessed the relative importance of dissolved H-2 and H2S as energy sources for the support of chemolithotrophic metabolism in an acidic geothermal spring in Yellowstone National Park. H2S and H-2 concentration gradients were observed in the outflow channel, and vertical H2S and O-2 gradients were evident within the microbial mat. H2S levels and microbial consumption rates were approximately three orders of magnitude greater than those of H-2. Hydrogenobaculum-like organisms dominated the bacterial component of the microbial community, and isolates representing three distinct 16S rRNA gene phylotypes (phylotype = 100% identity) were isolated and characterized. Within a phylotype, O-2 requirements varied, as did energy source utilization: some isolates could grow only with H2S, some only with H-2, while others could utilize either as an energy source. These metabolic phenotypes were consistent with in situ geochemical conditions measured using aqueous chemical analysis and in-field measurements made by using gas chromatography and microelectrodes. Pure-culture experiments with an isolate that could utilize H2S and H-2 and that represented the dominant phylotype (70% of the PCR clones) showed that H2S and H-2 were used simultaneously, without evidence of induction or catabolite repression, and at relative rate differences comparable to those measured in ex situ field assays. Under in situ-relevant concentrations, growth of this isolate with H2S was better than that with H-2. The major conclusions drawn from this study are that phylogeny may not necessarily be reliable for predicting physiology and that H2S can dominate over H-2 as an energy source in terms of availability, apparent in situ consumption rates, and growth-supporting energy.