On March 26, 2021, Dr. Zhang Yuzhong’s team in State Key Laboratory of Microbial Technology of Shandong University published a research paper entitled “Oxidation of trimethylamine to trimethylamine N-oxide facilitates high hydrostatic pressure tolerance in a generalist bacterial lineage” in Science Advances. After the article was published, Nature Research Highlights reported this work with the title of "How deep-sea bacteria thrive under pressure". Vice professor Qin Qilong and Dr. Wang Zhibin are the co-first authors, professor Zhang Yuzhong is corresponding author,and Shandong University is the first author institute.

The deep ocean biosphere represents one of the largest ecosystems on Earth and more than 10²⁹microbial cells exist there. High hydrostatic pressure (HHP) is a characteristic environmental factor of deep ocean. To survive under HHP condition, deep-sea microbes develop multiple strategies to cope with HHP, such as increasing membrane fluidity or fine tuning their cellular metabolism. However, it remains unclear whether adaption to HHP will drive the evolution of specific gene sets to cope with HHP.

This study identifieda two-step metabolism pathway to cope with HHP stress in a piezotolerant bacteriumMyroides profundiD25^T, which was isolated from a deep-sea sediment, can take up trimethylamine (TMA) through a novel TMA transporter TmaT, and oxidize intracellular TMA into trimethylamineN-oxide (TMAO) by a TMA monooxygenaseMpTmm. The produced TMAO was accumulated in the cell, functioning as a piezolyte improving both growth and survival at HHP. The function of the TmaT-MpTmm pathway was further confirmed by introducing it intoEscherichia coliandBacillus subtilis. TmaT-like andMpTmm-like sequences extensively exist in marine metagenomes. Other marineBacteroidetesbacteria containing genes encoding TmaT-like andMpTmm-like proteins also have improved HHP tolerance in the presence of TMA, implying the universality of this HHP tolerance strategy in marineBacteroidetes. This is the first report of the functional genes and mechanisms related to stress tolerance of deep-sea microorganisms. This research provides a new clue for understanding deep-sea life.

Professor Zhang Yuzhong's research team has been engaged in marine microbiology for a long time. In recent years, a series of research results have been achieved in the fields of marine microbial diversity and evolution, unique life characteristics, extreme environmental adaptation and ecological effects. The research results published in Science Advances this time are another research progress made by the team in the field of marine microbiology and microbial oceanography.

This work was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, the Major Basic Program of Natural Science Foundation of Shandong Province et al..Scholars from Shandong University, Ocean University of China, Qingdao Marine Science and Technology Pilot National Laboratory, Shanghai Ocean University and the University of Warwick participated in this work.

Link to the paper:https://doi.org/10.1126/sciadv.abf9941.

Link to Nature research highlights: https://www.nature.com/articles/d41586-021-00829-y.