Characterization of Terrihabitans soli gen. nov., sp. nov., a Novel 0.2 μm-Filterable Soil Bacterium Belonging to a Widely Distributed Lineage of Hyphomicrobiales ( Rhizobiales )

• Published in: Diversity
• Main Authors: Ryosuke Nakai, Takeshi Naganuma, Nozomi Tazato, Tadao Kunihiro, Sho Morohoshi, Tomomi Koide, Hiroyuki Kusada, Hideyuki Tamaki, Takashi Narihiro
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: filter sterilization; filterable bacteria; soil; phylogeny; taxonomy; Hyphomicrobiales; Biology (General); QH301-705.5; Arctic; Norway
• Online Access: https://doi.org/10.3390/d13090422; https://doaj.org/article/5ff9c39acc5a4d16be4661e1be2392c5

We previously showed that novel filterable bacteria remain in “sterile” (<0.2 μm filtered) terrestrial environmental samples from Japan, China, and Arctic Norway. Here, we characterized the novel filterable strain IZ6 T , a representative strain of a widely distributed lineage. Phylogenetic analysis showed that this strain was affiliated with the Rhizobiales (now proposed as Hyphomicrobiales ) of Alphaproteobacteria , but distinct from any other type strains. Strain IZ6 T shared the following chemotaxonomic features with the closest (but distantly) related type strain, Flaviflagellibacter deserti SYSU D60017 T : ubiquinone-10 as the major quinone; phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol as major polar lipids; and slightly high G+C content of 62.2 mol%. However, the cellular fatty acid composition differed between them, and the unsaturated fatty acid (C 18:1 ω 7 c /C 18:1 ω 6 c ) was predominantly found in our strain. Moreover, unlike methyrotrophs and nitrogen-fixers of the neighboring genera of Hyphomicrobiales ( Rhizobiales ), strain IZ6 T cannot utilize a one-carbon compound (e.g., methanol) and fix atmospheric nitrogen gas. These findings were consistent with the genome-inferred physiological potential. Based on the phylogenetic, physiological, and chemotaxonomic traits, we propose that strain IZ6 T represents a novel genus and species with the name Terrihabitans soli gen. nov., sp. nov. (=NBRC 106741 T = NCIMB 15058 T ). The findings will provide deeper insight into the eco-physiology of filterable microorganisms.