Hydrogen Utilization Potential in Subsurface Sediments.
Hydrogen Utilization Potential in Subsurface Sediments.
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DOI：
10.3389/fmicb.2016.00008
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发表时间：
2016
影响因子：
5.2
通讯作者：
Kallmeyer J
中科院分区：
文献类型：
--
作者：
Adhikari RR;Glombitza C;Nickel JC;Anderson CH;Dunlea AG;Spivack AJ;Murray RW;D'Hondt S;Kallmeyer J
地下微生物群落进行许多终端电子接受过程，通常是同时进行的。使用基于氚的分析方法，我们测量了几种具有不同主要电子受体的地下沉积环境(凡湖、巴伦支海、赤道太平洋和墨西哥湾)中氢酶催化的潜在氢氧化。氢酶是由利用分子氢作为代谢底物、产物或中间体的微生物所表达的一个不同的酶家族。该分析揭示了利用分子氢的潜力，并允许对微生物活动进行定性检测，而不考虑主要的电子接受过程。由于该方法只需要回收后立即冷冻的样本，因此该检测方法可以用于鉴定地下生态系统中的微生物活动，而不需要保存活的材料。我们在几个地点测量了来自多个深度的所有样本的潜在氢氧化速率，这些地点总共跨越了广泛的环境条件和生物地球化学区。归一化为细胞总丰度的潜在活性范围超过五个数量级，并随主要终端电子受体的不同而变化。最低的单位细胞电位率是硝酸盐还原区域的特征，而最高的单位细胞电位率出现在产甲烷区。这种关系与主要电子受体的关系可能包括：(1)在连续较深的生物地球化学带中发酵的重要性增加；(2)在连续较深的带中H_2酶对连续较高浓度的H_2的适应。
Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material. We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i) increasing importance of fermentation in successively deeper biogeochemical zones and (ii) adaptation of H2ases to successively higher concentrations of H2 in successively deeper zones.