Thermus brevis sp. nov., a moderately thermophilic bacterium isolated from a hot spring microbial mat

Abstract

Three closely related, facultative anaerobic, Gram-stain-negative, twitching motile, short rod-shaped, non-endospore-forming, moderately thermophilic bacteria, designated strains SYSU G05001T, SYSU G05003 and SYSU G05004, were isolated from a hot spring microbial mat, collected from Rehai National Park, Tengchong, Yunnan Province, south-western China. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that these three strains were closely related to Thermus scotoductus SE-1T (97.97, 98.18, 97.90 % sequence similarity). Whole genome sequencing and polyphasic taxonomic approach were used to determine the genomic profile and taxonomic status of the novel strain SYSU G05001T. Cell growth occurred at 37–80 °C (optimum, 55 °C), pH 6.0–8.0 (optimum, pH 7.0) and with 0–3.0 % (w/v) NaCl (optimum, 1%). Thiosulfate enhanced cell growth. MK-8 was the predominant menaquinone. The major cellular fatty acids included iso-C15 : 0, iso-C17 : 0 and anteiso-C15 : 0. The major polar lipids were consisted of aminophospholipid, glycolipid and phospholipids. The whole genome of strain SYSU G05001T consisted of 2.55 Mbp and the DNA G+C content was 64.94 mol%. The average nucleotide identity (≤94.95 %) and digital DNA–DNA hybridization (≤62.3 %) values between strain SYSU G05001T and other members of the genus Thermus were all lower than the threshold values recommended for distinguishing novel prokaryotic species. On the basis of the presented polyphasic evidence and genotypic data, it is proposed that strain SYSU G05001T (=KCTC 82627T=MCCC 1K06118T) represents a novel species of the genus Thermus , for which the name Thermus brevis sp. nov. is proposed.