Hadal trenches form where one tectonic plate descends beneath another, creating the deepest ocean habitats. Despite extreme pressure and limited energy supply, their microbiomes sustain biogeochemical cycling and support trench ecosystems. In this Review, we synthesize culture-based studies, single cell genomics and metagenomic surveys to (1) map the distribution of bacterial and archaeal lineages, (2) examine adaptations involving membranes, proteins, genome maintenance and nutrient use, (3) describe microbial roles across oxic and anoxic sediment zones, (4) assess partnerships between microbes and trench fauna, and (5) evaluate the biotechnological potential of extremozymes and bioactive compounds. Moreover, we compare patterns across studied trenches and identify major uncertainties caused by limited sampling, cultivation and in situ experimentation. By doing so, this Review provides a roadmap for targeted isolation, in situ experimentation and the discovery of uncommon extremozymes and bioactive compounds. Hadal trench microbes thrive under extreme conditions, and actively shape ecosystem functions through nutrient regeneration, energy flow, and interdependent relationships
A. Barcan, R. Barcan, Li-Sheng He et al.· Communications Earth & Envir...· 0 citations
The Eboliang Hu saline lakes in the hyper-arid Qaidam Basin is a high-altitude, weakly acidic hypersaline system with strong environmental gradients and limited nitrogen availability. To resolve its microbial ecology and evolutionary context, we performed genome-resolved metagenomic sequencing across four distinct habitats, reconstructing 46 medium- to high-quality metagenome-assembled genomes (MAGs) and a comprehensive gene catalog. The community shows pronounced spatial heterogeneity and is dominated by Thermodesulfobacteriota, Pseudomonadota, Bacteroidota, and archaeal lineages. Phylogenomic placement and large-scale sequence comparisons indicate that multiple dominant taxa exhibit affinity to marine- and subsurface-associated reference lineages, consistent with long-term isolation of a marine-derived ecosystem about 10–11 million years ago. Functional reconstruction reveals a distributed metabolic system in which carbon, nitrogen, and sulfur cycling are partitioned across taxa. Notably, hydrogen oxidation and arsenite oxidation are recurrent energy-producing strategies across dominant lineages, indicating redox flexibility under oligotrophic conditions. Comparative genomics further suggests lineage-specific adaptations to osmotic stress, UV exposure, and nutrient limitation. Horizontal gene transfer and phylogenetic incongruence among key metabolic genes indicate that co-evolutionary processes and gene exchange have contributed to functional innovation. These findings provide a framework for understanding microbial persistence and evolution in isolated extreme environments and offer potential analogs for extraterrestrial habitability.
Haoran Wang, Chunhui Ai, A. Barcan et al.· bioRxiv· 0 citations
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