Alkalibacter rhizosphaerae sp. nov., a CO-utilizing bacterium isolated from tidal flat sediment, and emended description of the genus Alkalibacter

Abstract

A novel anaerobic, rod-shaped, non-motile bacterium, designated strain ES005T, was isolated from tidal flat sediments near the rhizosphere of Phragmites australis at Eulsukdo Island, Republic of Korea. A polyphasic approach revealed that cells of the strain were Gram-stain-positive, catalase-and oxidase-negative, non-spore-forming rods. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain ES005T belonged to the family Eubacteriaceae, class Clostridia and showed the highest sequence similarity to Alkalibacter mobilis (97.52%) and followed by Alkalibacter saccharofermentans Z-79820T (96.72%). The OrthoANI value between strain ES005T and A. mobilis was 69.67%. Strain ES005T grew optimally at 33–37 °C, at pH 6.0–7.0 and in the presence of 1–2% (w/v) NaCl. Growth in 12.5% CO atmosphere was observed. Acetate and formate were end products of fructose fermentation and growth on CO. The major cellular fatty acids of strain ES005T were C14:0 (39.1%) and C16:0 (26.6%). The major polar lipids were diphoshatidylgycerol, phosphatidylglycerol and three unidentified phospholipids. The DNA G+C content of strain ES005T was 46.9mol%. Based on the phenotypic, phylogenetic, genomic and chemotaxonomic features of the isloate, strain ES005T represents a novel species, for which the name Alkalibacter rhizosphaerae sp. nov. is proposed. The type strain is ES005T (=KCTC 25246T=JCM 34530T). © 2022 The Authors.