Researchers at Hokkaido University and the Woods Hole Oceanographic Institution have uncovered a new bacterial species at a deep-sea hydrothermal vent, offering fresh insights into bacterial evolution. This discovery, made at the 'Crab Spa' vent site, highlights the role of these unique ecosystems in fostering diverse microbial communities.

Deep-sea hydrothermal vents, akin to underwater hot springs, facilitate the movement of heated, nutrient-rich water from beneath the ocean crust to the surface. These areas, devoid of sunlight, are bustling with life, thanks to microbes that utilize chemosynthesis, a process similar to photosynthesis in plants, to produce energy.

The team's work focused on exploring microbial diversity in these environments. They successfully isolated a new campylobacterial strain, Hydrogenimonas cancrithermarum, named after its discovery site. This research, published in the International Journal of Systematic and Evolutionary Microbiology, delves into the ecological significance of the Campylobacteria class, known for its role in primary production at hydrothermal vents and its presence in various pathogenic species.

Hydrogenimonas, a genus adapted to high temperatures, was previously known for only two species. The new mesophilic (moderate temperature-adapted) and sulfur-oxidizing strain expands the genus's known physiological and metabolic traits. Assistant Professor Sayaka Mino from Hokkaido University suggests that this strain could be key to understanding evolutionary shifts in temperature adaptation and metabolic lifestyles within the genus.

The researchers conducted a genome comparison across Campylobacteria, uncovering conserved genes in the phosphotransacetylase-acetate kinase (Pta-AckA) pathway. This pathway, significant in a pathogenic Campylobacter species for host colonization, might have been crucial in Hydrogenimonas's adaptation from deep-sea environments to other habitats.

Despite the prevalence of metagenomic sequencing in studying microbial diversity, Mino emphasizes the importance of cultivation-based approaches, as demonstrated by the unique characteristics of this new Hydrogenimonas strain. The team plans to continue exploring culturable species to deepen our understanding of Campylobacteria diversity.

Journal Reference:

1. Sayaka Mino, So Fukazawa, Jiro Tsuchiya, Jesse C. McNichol, Stefan M. Sievert, Shogo Yamaki, Yasuhiro Ando, Tomoo Sawabe. Hydrogenimonas cancrithermarum sp. nov., a hydrogen- and thiosulfate-oxidizing mesophilic chemolithoautotroph isolated from diffuse-flow fluids on the East Pacific Rise, and an emended description of the genus Hydrogenimonas. International Journal of Systematic and Evolutionary Microbiology, 2023; 73 (11) DOI: 10.1099/ijsem.0.006132