Chinese scientists unveil microbial oasis in ocean's deepest trenches

Chinese scientists have revealed a hidden microbial oasis in the depths of the Earth's oceanic trenches, pushing the boundaries of research on the hadal zone, the deepest part of the ocean floor, from ecological mapping to principle analysis and resource exploration.

According to experts, the research indicates China's leading position in the field of deep-sea life sciences.

A perspective article and three research papers about the study were published as a special issue in the journal Cell Host & Microbe recently. Journal editors praised the study for uncovering the previously underestimated genetic diversity and microbial processes in the ocean's deepest regions.

This publication follows the team's initial findings from the scientific initiative "Mariana Trench Environment and Ecology Research", or MEER, which were published in the journal Cell as a cover feature in March last year.

The initiative was a joint effort of Shanghai Jiao Tong University, the Institute of Deep-sea Science and Engineering of the Chinese Academy of Sciences, and genome research organization BGI Group, with professor Xiao Xiang from SJTU as the convening scientist.

Located at depths exceeding 6,000 meters, the trenches are among the most extreme environments on the Earth, once considered lifeless zones. Riding China's self-developed human occupied vehicle Fendouzhe, the first phase of the research elucidated the life adaptation strategies and species composition of the trench ecosystems, creating the first ecological map of the ocean's deepest environments.

In its second phase, the research team overcame challenges in studying microorganisms in such extreme environments, including low biomass, low extraction success rates, and difficulties in activity identification. They achieved this through the development of an innovative nucleic acid-protein co-extraction and co-analysis technique, and thus constructed MEER-APD, a deep-sea specific dataset containing over 135,000 non-redundant active proteins, of which more than 95 percent are unique to the hadal zone.

Altogether, the team integrated more than 2,100 deep-sea metagenomic samples from around the world, including those from the hadal zone, and constructed a deep-sea gene catalog, which comprises 502 million non-redundant genes.

They also predicted over 2.4 million representative protein structures, creating the world's largest deep-sea gene resource map and protein structure repository to date. All of these findings have been incorporated into the world's largest hadal zone biological database, constructed by the MEER initiative.

The database is open to the international scientific community, aiming to contribute Chinese expertise to the understanding of the ocean's deepest realms and the development of deep-sea resource repositories.