Spatial variations of microbial communities in abyssal and hadal sediments across the Challenger Deep

Abstract

Microbial communities in hadal sediments are least explored in hadal zone (>6,000 m), especially in the Challenger Deep with high pressure (∼110 M pa at the bottom). In this study, we investigated the microbial communities in the sediments of the slope and trench-axis bottom of the Challenger Deep in the Mariana Trench. Classification of the reads of the 16S rRNA gene amplicons showed vertical distribution of prokaryotic microbial inhabitants from the surface to up to 60 centimeter below surface floor (cmbsf). The most dominant phyla were Proteobacteria, Chloroflexi, Actinobacteria, Planctomycetes and candidate phyla Patescibacteria and Marinimicrobia. Distinct dominant groups in the microbial communities were observed in trench-axis sediment (water depth >8,600 m), compared to the slopes of the Challenger Deep. A sampling site at the northern slope was enriched with archaea from mesophilic Euryarchaeota Marine Group II (MGII) as a biomarker of specific geochemical setting. Among archaeal community, Thaumarchaeota represented by Nitrosopumilus were dominant in the upper layers and diminished drastically in the deeper layers. “Ca. Woesearchaeota”, however, became the dominant group in the deeper layers. Overall, our study provides a better understanding on the pattern of the microbial communities in the deepest hadal sediments on Earth, and highlights the extraordinary diversity still waiting to be discovered.

Microbial community and geochemical analyses of trans-trench sediments for understanding the roles of hadal environments

“…Conversely, Proteobacteria and Thaumarchaeota dominated in shallower sections. These trends are similar to previous studies [20, 21, 48, 54–56]. and likely depend on the concentrations of dissolved oxygen and nitrate in sediments.…”

“…S8). In general, the dominant phyla were similar to those of previous studies of abyssal and hadal sediments [20, 21, 48, 54–56].…”

“…Therefore, the intrinsic organic carbon sources in hadal zones are considered to facilitate establishment of distinctive faunal and prokaryotic biospheres observed at global scales [15–19]. Recently, the influence of physicochemical features on hadal biospheres were reported for microbial communities in the Mariana and the Kermadec Trench regions under oligotrophic oceans [20, 21]. However, except for the cases, microbial community structures in hadal sediments were not compared with adjacent abyssal regions [2], and such comparison under eutrophic oceanic regions have not been investigated yet.…”

Rhodobacterales and Rhizobiales Are Associated With Stony Coral Tissue Loss Disease and Its Suspected Sources of Transmission

“…Our results showed that sediment and water microbial betadiversity was significantly different among vulnerable, endemic, and epidemic SCTLD zones (Figure 3). Water and sediments collected from distinct geographical regions can have discrete microbial compositions (Cui et al, 2019;Glasl et al, 2019). Although geographical location may have been the main factor driving site groupings (Glasl et al, 2019), this pattern is intertwined with the unique environmental conditions from FIGURE 10 | Rhizobiales and Rhodobacterales found in sediment and water samples that were significantly differentiated in diseased colony lesions.…”

Microbial community and geochemical analyses of trans-trench sediments for understanding the roles of hadal environments

“…Therefore, the labile organic carbon deposition in hadal zone supported by the high sedimentation is considered to facilitate establishment of distinct faunal and prokaryotic community observed at global scales [15][16][17][18][19]. Recently, the influence of physicochemical features on hadal biospheres were reported for microbial communities in the Mariana and Kermadec Trench regions [20,21], where under oligotrophic and relatively eutrophic (intermediate) ocean, respectively [22,23]; the pioneering studies reported microbial biodiversity in hadal trench bottom, trench slope, and adjusted abyssal plain sediments using culture-independent highthroughput sequencing techniques, and consequently demonstrated the structural similarity among each abyssal and hadal site. However, relations between geochemistry and microbial composition in hadal trench bottom and adjacent abyssal sediments have been still uninvestigated.…”