Metatranscriptomic evidence of pervasive and diverse chemolithoautotrophy relevant to C, S, N and Fe cycling in a shallow alluvial aquifer.
Metatranscriptomic evidence of pervasive and diverse chemolithoautotrophy relevant to C, S, N and Fe cycling in a shallow alluvial aquifer.
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在浅层冲积含水层中，与C，S，N和Fe循环相关的普遍和多样化的化学洋原体的元共转录。
DOI：
10.1038/ismej.2016.25
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发表时间：
2016-09
期刊：
影响因子：
--
通讯作者：
Beller HR
中科院分区：
文献类型：
--
作者：
Jewell TN;Karaoz U;Brodie EL;Williams KH;Beller HR
地下水生态系统通常被认为是由地表衍生的异地有机质提供动力，并由生活在通常是寡养条件下的异养微生物主导。然而，在对Rifle(CO)一个常年亚缺氧含水层进行的为期2个月的硝酸盐修正研究中，菌株解析的后转录分析揭示了与C、S、N和Fe循环相关的普遍和多样化的化石自养细菌活性。在注射硝酸盐之前，厌氧氨氧化(Anammox)细菌占总微生物群落基因表达的16%，而在注射硝酸盐时，另外两类化学自养细菌共同占转录组的80%：(1)铁(II)氧化蒜科成员和(2)S氧化物种的菌株，脱氮硫单胞菌。值得注意的是，这三个群体所占的超基因组比例远远高于他们所代表的超基因组覆盖的比例。转录分析揭示了一些意想不到的代谢偶联，特别是在名义上嗜氧的Gallionellaceae菌株之间，推测依赖于硝酸盐的Fe(II)和S氧化，包括周质(NapAB)和膜结合(NarGHI)硝酸还原酶的表达。在这项研究中，化学自养细菌的三个最活跃的类群具有重叠的代谢，这使得它们在整个研究过程中占据了不同但相关的代谢生态位。总体而言，这些结果突显了化学自养在含水层生物地球化学循环中的重要作用，这一发现对理解陆地碳循环具有广泛影响，并得到最近对不同地球化学类型含水层的研究的支持。
Groundwater ecosystems are conventionally thought to be fueled by surface-derived allochthonous organic matter and dominated by heterotrophic microbes living under often-oligotrophic conditions. However, in a 2-month study of nitrate amendment to a perennially suboxic aquifer in Rifle (CO), strain-resolved metatranscriptomic analysis revealed pervasive and diverse chemolithoautotrophic bacterial activity relevant to C, S, N and Fe cycling. Before nitrate injection, anaerobic ammonia-oxidizing (anammox) bacteria accounted for 16% of overall microbial community gene expression, whereas during the nitrate injection, two other groups of chemolithoautotrophic bacteria collectively accounted for 80% of the metatranscriptome: (1) members of the Fe(II)-oxidizing Gallionellaceae family and (2) strains of the S-oxidizing species, Sulfurimonas denitrificans. Notably, the proportion of the metatranscriptome accounted for by these three groups was considerably greater than the proportion of the metagenome coverage that they represented. Transcriptional analysis revealed some unexpected metabolic couplings, in particular, putative nitrate-dependent Fe(II) and S oxidation among nominally microaerophilic Gallionellaceae strains, including expression of periplasmic (NapAB) and membrane-bound (NarGHI) nitrate reductases. The three most active groups of chemolithoautotrophic bacteria in this study had overlapping metabolisms that allowed them to occupy different yet related metabolic niches throughout the study. Overall, these results highlight the important role that chemolithoautotrophy can have in aquifer biogeochemical cycling, a finding that has broad implications for understanding terrestrial carbon cycling and is supported by recent studies of geochemically diverse aquifers.