Plantibacter lichenum sp. nov., isolated from two lichen samples collected from Shangri-La, Southwest of China

Two novel bacterial strains, designated YIM 135249T and YIM 135347, were isolated from two distinct species of lichen samples collected from Shangri-La, Southwest of China. The strains were Gram-stain-positive, catalase-positive, oxidase-negative, aerobic, yellow-pigmented, non-motile and short rod-shaped. Growth occurred at 10-35 °C (optimum 28 °C), pH 4.0-9.0 (optimum pH 7.0) and with 0-9.0% sodium chloride (NaCl, w/v, optimum 0%). Menaquinone (MK)-10 and MK-11 were the predominant respiratory quinones, while polar lipids included phosphatidylglycerol, diphosphatidylglycerol and an unidentified glycolipid. Major fatty acids included iso-C16:0, anteiso-C15:0 and anteiso-C17:0. The 16S rRNA gene sequences of strains YIM 135249ᵀ and YIM 135347 showed the highest similarity (98.6%) to those of the type strains Plantibacter flavus NBRC 103081ᵀ and Plantibacter auratus NBRC 15702ᵀ. Phylogenetic analyses based on both the 16S rRNA gene and whole-genome sequences revealed that the two strains formed a distinct clade within the genus Plantibacter. Genome-based comparisons further supported their taxonomic distinctiveness, with average nucleotide identity (ANI) values ≤78.8% and digital DNA-DNA hybridization (dDDH) values ≤23.1% between strain YIM 135249ᵀ and the type strains of recognized Plantibacter species. The dDDH and ANI values between strains YIM 135249ᵀ and YIM 135347 were 82.0% and 97.9%, respectively. The genomic G+C contents were 67.3 and 67.5 mol%. On the basis of phenotypic and genotypic data, strains YIM 135249ᵀ and YIM 135347 represent a novel species of the genus Plantibacter, for which the name Plantibacter lichenum sp. nov. is proposed, with YIM 135249ᵀ as the type strain (=MCCC 1K09942T=NBRC 117222T).