Hymenobacter siberiensis sp. nov., isolated from a marine sediment of the East Siberian Sea and Hymenobacter psoromatis sp. nov., isolated from an Antarctic lichen

Gram-stain-negative, strictly aerobic, red-pink-coloured, rod-shaped and non-motile bacterial strains PAMC 29290, PAMC 29294(T) and PAMC 29296 were isolated from marine surface sediment sampled in the East Siberian Sea and strains PAMC 26553 and PAMC 26554(T) were obtained from an Antarctic lichen. Strains PAMC 29290, PAMC 29294(T) and PAMC 29296 were closely related to Hymenobacter artigasi (98.8% 16S rRNA gene similarity), Hymenobacter antarcticus (97.3%) and Hymenobacter glaciei (96.9%), and PAMC 26553 and PAMC 26554(T) showed high similarity to Hymenobacter ginsengisoli (97.0%), Hymenobacter rivuli (96.1%) and Hymenobacter setariae (95.9%). Genomic relatedness analyses showed that strains PAMC 29290, PAMC 29294(T) and PAMC 29296 could be distinguished from H. artigasi by average nucleotide identity (ANI; 93.1-93.2%) and digital DNA-DNA hybridization (dDDH; 50.3-51.0%) values. Strains PAMC 26553 and PAMC 26554(T) could be clearly distinguished from H. ginsengisoli with ANI values <79.8% and dDDH values <23.3%. The major fatty acids of strains PAMC 29290, PAMC 29294(T) and PAMC 29296 were C-15:0 iso (21.0-26.0%), summed feature 3 (C-16:1, omega 7c and/or C-16:1, omega 6c; 17.4-18.2%), C-15:0 anteiso (12.7-19.1%) and summed feature 4 (C-17:1 iso I and/or anteiso B; 8.6-16.1%) and those of strains PAMC 26553 and PAMC 26554(T) were summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c; 20.7-22.2%), C-15:0 anteiso (17.5-19.7%) and summed feature 4 (C-17:1 iso I and/or anteiso B; 15.5-18.1%). The major respiratory quinone was MK-7. The genomic DNA G+C contents were 60.6-60.8 mol%. The polar lipids of PAMC 29294(T) were found to consist of phosphatidylethanolamine, four unidentified aminolipids, an unidentified aminophospholipid and five unidentified lipids; those of PAMC 26554(T) were phosphatidylethanolamine, three unidentified aminolipids, four unidentified aminophospholipid and two unidentified lipids. The distinct phylogenetic position and some physiological characteristics distinguished the novel strains from closely related type strains in the genus Hymenobacter. Thus, two novel species are proposed, with the names Hymenobacter siberiensis sp. nov. (type strain, PAMC 29294(T)=KCTC 82466(T)=JCM 34574(T)) and Hymenobacter psoromatis sp. nov. (type strain, PAMC 26554(T)=KCTC 82464(T)=JCM 34572(T)), respectively.

Automated summary

In this study, five bacterial strains belonging to the genus Hymenobacter were isolated from different sources. Two novel species, named Siberiensis and Psoromatis, were proposed based on their distinct phylogenetic position and physiological characteristics.