Lichenihabitans psoromatis gen. nov., sp. nov., a member of a novel lineage (Lichenihabitantaceae fam. nov.) within the order of Rhizobiales isolated from Antarctic lichen

Abstract

Two Gram-stain-negative, facultative anaerobic chemoheterotrophic, pink-coloured, rod-shaped and non-motile bacterial strains, PAMC 29128 and PAMC 29148(T), were isolated from lichen. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strains PAMC 29128 and PAMC 29148(T) belong to lichen-associated Rhizobiales-1 (LAR1), an uncultured phylogenetic lineage of the order Rhizobiales and the most closely related genera were Methylocapsa (<93.9 %) and Methylosinus (<93.8 %). The results of phylogenomic and genomic relatedness analyses also showed that strains PAMC 29128 and PAMC 29148(T) were clearly distinguished from other species in the order Rhizobiales with average nucleotide identity values of <71.4% and genome-to-genome distance values of <22.7 %. Genomic analysis revealed that strains PAMC 29128 and PAMC 29148(T) did not contain genes involved in atmospheric nitrogen fixation or utilization of carbon compounds such as methane and methanol. Strains PAMC 29128 and PAMC 29148(T) were able to utilize certain monosaccharides, disaccharides, sugar alcohols and other organic compounds as a sole carbon source. The major fatty acids (>10%) were summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c; 33.7-39.7 %), summed feature 3 (C-16:1 omega 7c and/or C-16(:1) omega 6c; 25.2-254%) and C-19:0 cyclo omega 8c (11.9-15.4%). The major respiratory quinone was Q-10. The genomic DNA G+C contents of PAMC 29128 and PAMC 29148(T) were 63.0 and 63.1 mol%, respectively. Their distinct phylogenetic position and some physiological characteristics support the proposal of Lichenihabitans gen. nov., with the type species Lichenihabitans psoromatis sp. nov. (type strain, PAMC 29148(T)=KCCM 43293(T)=JCM 33311(T)). Lichenihabitantaceae fam. nov. is also proposed.