Graw Michael F, D'Angelo Grace, Borchers Matthew, Thurber Andrew R, Johnson Joel E, Zhang Chuanlun, Liu Haodong, Colwell Frederick S
College of Earth, Ocean, and Atmospheric Science, Oregon State University, Corvallis, OR, United States.
Department of Microbiology, College of Science, Oregon State University, Corvallis, OR, United States.
Front Microbiol. 2018 Apr 11;9:729. doi: 10.3389/fmicb.2018.00729. eCollection 2018.
The deep marine subsurface is a heterogeneous environment in which the assembly of microbial communities is thought to be controlled by a combination of organic matter deposition, electron acceptor availability, and sedimentology. However, the relative importance of these factors in structuring microbial communities in marine sediments remains unclear. The South China Sea (SCS) experiences significant variability in sedimentation across the basin and features discrete changes in sedimentology as a result of episodic deposition of turbidites and volcanic ashes within lithogenic clays and siliceous or calcareous ooze deposits throughout the basin's history. Deep subsurface microbial communities were recently sampled by the International Ocean Discovery Program (IODP) at three locations in the SCS with sedimentation rates of 5, 12, and 20 cm per thousand years. Here, we used Illumina sequencing of the 16S ribosomal RNA gene to characterize deep subsurface microbial communities from distinct sediment types at these sites. Communities across all sites were dominated by several poorly characterized taxa implicated in organic matter degradation, including , and . Sulfate-reducing bacteria comprised only 4% of the community across sulfate-bearing sediments from multiple cores and did not change in abundance in sediments from the methanogenic zone at the site with the lowest sedimentation rate. Microbial communities were significantly structured by sediment age and the availability of sulfate as an electron acceptor in pore waters. However, microbial communities demonstrated no partitioning based on the sediment type they inhabited. These results indicate that microbial communities in the SCS are structured by the availability of electron donors and acceptors rather than sedimentological characteristics.
深海次表层是一个异质环境，其中微生物群落的组装被认为受有机物质沉积、电子受体可用性和沉积学的综合控制。然而，这些因素在构建海洋沉积物中微生物群落的相对重要性仍不清楚。南海（SCS）整个盆地的沉积作用存在显著变化，并且由于在整个盆地历史中，浊积岩和火山灰在成岩粘土以及硅质或钙质软泥沉积物中的幕式沉积，其沉积学具有离散变化。国际大洋发现计划（IODP）最近在南海的三个地点采集了深海次表层微生物群落样本，这些地点的沉积速率分别为每千年5厘米、12厘米和20厘米。在这里，我们使用16S核糖体RNA基因的Illumina测序来表征这些地点不同沉积物类型的深海次表层微生物群落。所有地点的群落都由几种与有机物质降解有关但特征描述不佳的分类群主导，包括 ，以及 。在来自多个岩芯的含硫酸盐沉积物中，硫酸盐还原菌仅占群落的4%，并且在沉积速率最低的地点的产甲烷带沉积物中，其丰度没有变化。微生物群落明显受沉积物年龄和孔隙水中作为电子受体的硫酸盐可用性的影响。然而，微生物群落并没有根据它们所栖息的沉积物类型进行划分。这些结果表明，南海的微生物群落是由电子供体和受体的可用性而非沉积学特征构建的。
