Abstract In recent decades, microbial diversities in different hydrothermal regions of the Okinawa Trough have been elucidated. However, the microbial community compositions in non-hydrothermal sites in the Okinawa Trough are unclear. In this study, we analyzed the microbial communities at three different non-hydrothermal sites from two depths in the Mid-Okinawa Trough. The bacterial and archaeal diversities, which were dominated by Gammaproteobacteria and Thaumarchaeota, respectively, were similar in the surface sediments (samples CW12A, CW27A, and CW28A) and grouped together. However, the microbial communities in deeper habitats (samples CW12B, CW27B, and CW28B) were completely different. The microbial diversities in the CW12B and CW28B samples, which were significantly different from that in sample CW27B, were more closely related and grouped together. In sample CW27B, the most abundant bacterial and archaeal groups were Gammaproteobacteria and Hadesarchaea, respectively. In samples CW12B and CW28B, Firmicutes was the major bacterial phylum and the major archaeal phyla were Lokiarchaeota and Bathyarchaeota. These results indicate that the microbial community composition in relatively deep samples from non-hydrothermal fields appears to be more diverse and distinct from that in surface sediments. In addition, all the reported microbial communities at hydrothermal and non-hydrothermal sites in the Okinawa Trough region were summarized. Both the bacterial and archaeal communities are variable at the different sampling sites. Even within a location, the microbial community compositions changed with depth. Overall, our work documents the microbial diversity at different sampling sites and varying depths in non-hydrothermal fields of the Mid-Okinawa Trough. This suggests that distinct microbial community compositions likely occur beneath the sediments in different non-hydrothermal Okinawa Trough regions.

中文翻译：

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冲绳海槽中部非热液沉积物中的可变微生物群落

摘要 近几十年来，冲绳海槽不同热液区的微生物多样性已被阐明。然而，冲绳海槽非热液区的微生物群落组成尚不清楚。在这项研究中，我们分析了冲绳海槽中部两个深度的三个不同非热液地点的微生物群落。细菌和古细菌的多样性分别以 Gammaproteobacteria 和 Thaumarchaeota 为主，在表层沉积物（样品 CW12A、CW27A 和 CW28A）中相似，并分组在一起。然而，更深的栖息地（样本 CW12B、CW27B 和 CW28B）中的微生物群落完全不同。CW12B 和 CW28B 样品中的微生物多样性与 CW27B 样品中的微生物多样性显着不同，更紧密地联系在一起并聚集在一起。在样品 CW27B 中，最丰富的细菌和古菌群分别是 Gammaproteobacteria 和 Hadesarchaea。在样品 CW12B 和 CW28B 中，厚壁菌门是主要的细菌门，主要的古菌门是 Lokiarchaeota 和 Bathyarchaeota。这些结果表明，来自非热液场的相对较深样品中的微生物群落组成似乎更加多样化，并且与表层沉积物中的微生物群落组成不同。此外，总结了冲绳海槽地区热液和非热液地点的所有报道的微生物群落。不同采样点的细菌和古菌群落都是可变的。即使在一个位置内，微生物群落组成也会随着深度而变化。全面的，我们的工作记录了冲绳中部海槽非热液区不同采样点和不同深度的微生物多样性。这表明不同的非热液冲绳海槽区域的沉积物下方可能存在不同的微生物群落组成。