Vertically distinct microbial communities in the Mariana and Kermadec trenches

Abstract

Hadal trenches, oceanic locations deeper than 6,000 m, are thought to have distinct microbial communities compared to those at shallower depths due to high hydrostatic pressures, topographical funneling of organic matter, and biogeographical isolation. Here we evaluate the hypothesis that hadal trenches contain unique microbial biodiversity through analyses of the communities present in the bottom waters of the Kermadec and Mariana trenches. Estimates of microbial protein production indicate active populations under in situ hydrostatic pressures and increasing adaptation to pressure with depth. Depth, trench of collection, and size fraction are important drivers of microbial community structure. Many putative hadal bathytypes, such as members related to the Marinimicrobia, Rhodobacteraceae, Rhodospirilliceae, and Aquibacter, are similar to members identified in other trenches. Most of the differences between the two trench microbiomes consists of taxa belonging to the Gammaproteobacteria whose distributions extend throughout the water column. Growth and survival estimates of representative isolates of these taxa under deep-sea conditions suggest that some members may descend from shallower depths and exist as a potentially inactive fraction of the hadal zone. We conclude that the distinct pelagic communities residing in these two trenches, and perhaps by extension other trenches, reflect both cosmopolitan hadal bathytypes and ubiquitous genera found throughout the water column.

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].…”

Diversity of culturable heterotrophic bacteria from the Mariana Trench and their ability to degrade macromolecules

“…Due to the rapid progress of deep-sea sampling techniques in recent years, the microbial community structures at different water depths of the Mariana Trench have been extensively studied by either 16S rRNA gene high-throughput sequencing (Nunoura et al 2015;Peoples et al 2018;Tarn et al 2016;Tian et al 2018) or metagenomic sequencing (Liu et al 2019c;Wang et al 2019). There have also Edited by Chengchao Chen.…”

In situ meta‐omic insights into the community compositions and ecological roles of hadal microbes in the Mariana Trench

“…Dominant species in hadal free‐living and particle‐associated microbial communities were then uncovered, which highlighted the potential importance of heterotrophy, sulfur‐cycling, and methane and hydrogen utilization within the hadal bottom waters of the Mariana Trench (Tarn et al ., ). The most recent comparative analysis of microbial communities in different trenches further indicated the occurrence of distinctive hadal biospheres in global trench environments (Nunoura et al ., ; Liu et al ., ; Peoples et al ., ).…”

“…Since then, hundreds of new microbial strains were isolated from hadal trenches and the composition of hadal microbial communities was also casually determined using culturing and/or conventional 16S rRNA gene cloning methods (Bartlett, 2009;Cao et al, 2014). Only recently, nextgeneration sequencing techniques facilitated the studies on hadal microbial communities and provided in-depth insight on them (Eloe et al, 2011a;Nunoura et al, 2015Nunoura et al, , 2016Tarn et al, 2016;Liu et al, 2018;Peoples et al, 2018;Wang et al, 2019a). Compositions of microbial assemblages in the Puerto Rico Trench (PRT) from 6000 m depth were the first hadal microbial communities reported using the improved sequencing techniques (Eloe et al, 2011a).…”