Biogeochemical Implications of N2O-Reducing Thermophilic Campylobacteria in Deep-Sea Vent Fields, and the Description of Nitratiruptor labii sp. nov

Muneyuki Fukushi; Sayaka Mino; Hirohisa Tanaka; Satoshi Nakagawa; Ken Takai; Tomoo Sawabe

doi:10.1016/j.isci.2020.101462

Biogeochemical Implications of N₂O-Reducing Thermophilic Campylobacteria in Deep-Sea Vent Fields, and the Description of Nitratiruptor labii sp. nov

iScience. 2020 Aug 15;23(9):101462. doi: 10.1016/j.isci.2020.101462. eCollection 2020 Sep 25.

Authors

Muneyuki Fukushi¹, Sayaka Mino¹, Hirohisa Tanaka¹, Satoshi Nakagawa^{2

3}, Ken Takai³, Tomoo Sawabe¹

Affiliations

¹ Laboratory of Microbiology, Faculty of Fisheries Sciences, Hokkaido University, 3-1-1, Minato-cho, Hakodate 041-8611, Japan.
² Laboratory of Marine Environmental Microbiology, Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
³ Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.

Abstract

Nitrous oxide (N₂O) is a potent greenhouse gas and has significantly increased in the atmosphere. Deep-sea hydrothermal fields are representative environments dominated by mesophilic to thermophilic members of the class Campylobacteria that possess clade II nosZ encoding nitrous oxide reductase. Here, we report a strain HRV44^T representing the first thermophilic campylobacterium capable of growth by H₂ oxidation coupled to N₂O reduction. On the basis of physiological and genomic properties, it is proposed that strain HRV44^T (=JCM 34002 = DSM 111345) represents a novel species of the genus Nitratiruptor, Nitratiruptor labii sp. nov. The comparison of the N₂O consumption ability of strain HRV44^T with those of additional Nitratiruptor and other campylobacterial strains revealed the highest level in strain HRV44^T and suggests the N₂O-respiring metabolism might be the common physiological trait for the genus Nitratiruptor. Our findings provide insights into contributions of thermophilic Campylobacteria to the N₂O sink in deep-sea hydrothermal environments.

Keywords: Biocatalysis; Earth Sciences; Geology; Geomicrobiology; Microbiology.