Global marine sediments harbor a large and highly diverse microbial biosphere, but the mechanism by which this biosphere is established during sediment burial is largely unknown. During burial in marine sediments, concentrations of easily metabolized organic compounds and total microbial cell abundance decrease. However, it is unknown whether some microbial clades increase with depth. We show total population increases in 38 microbial families over 3 cm of sediment depth in the upper 7.5 cm of White Oak River (WOR) estuary sediments. Clades that increased with depth were more often associated with one or more of the following: anaerobes, uncultured, or common in deep marine sediments relative to those that decreased. Maximum doubling times (in situ steady-state growth rates could be faster to balance cell decay) were estimated as 2 to 25 years by combining sedimentation rate with either quantitative PCR (qPCR) or the product of the fraction read abundance of 16S rRNA genes and total cell counts (FRAxC). Doubling times were within an order of magnitude of each other in two adjacent cores, as well as in two laboratory enrichments of Cape Lookout Bight (CLB), NC, sediments (average difference of 28% ± 19%). qPCR and FRAxC in sediment cores and laboratory enrichments produced similar doubling times for key deep subsurface uncultured clades Bathyarchaeota (8.7 ± 1.9 years) and Thermoprofundales/MBG-D (4.1 ± 0.7 years). We conclude that common deep subsurface microbial clades experience a narrow zone of growth in shallow sediments, offering an opportunity for selection of long-term subsistence traits after resuspension events.

中文翻译：

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近表面缺氧沉积物中深部地下微生物进化枝生长区的证据。

全球海洋沉积物蕴藏着一个巨大且高度多样化的微生物生物圈，但是在沉积物埋葬期间建立该生物圈的机制尚不清楚。在海洋沉积物中埋葬期间，易代谢有机化合物的浓度和总微生物细胞丰度降低。然而，尚不清楚一些微生物进化枝是否随深度增加。我们显示，在白橡树河（WOR）河口沉积物的上部7.5厘米的3厘米沉积深度内，38个微生物家族的总种群增加。随深度增加的进化枝通常与以下一种或多种相关：相对于减少的厌氧菌，未培养的或深海沉积物中常见的厌氧菌。最大倍增时间（原位通过将沉降速率与定量PCR（qPCR）或16S rRNA基因的阅读丰度分数与总细胞计数（FRAxC）的乘积相结合，可以将稳态生长速率更快地平衡细胞的衰变）估计为2至25年。 。在两个相邻岩心以及在北卡罗来纳州观望湾（CLB），北卡罗来纳州沉积物的两个实验室浓缩物中，加倍时间彼此相差一个数量级（平均差异为28％±19％）。沉积物核心和实验室浓缩中的qPCR和FRAxC对关键的深层地下未培养进化枝Bathyarchaeota（8.7±1.9年）和Thermoprofundales产生了类似的倍增时间/MBG-D（4.1±0.7年）。我们得出的结论是，常见的深层地下微生物进化枝在浅层沉积物中经历狭窄的生长区域，为重悬事件后长期生存特征的选择提供了机会。