Thermus Brevis Sp. Nov., a Moderately Thermophilic Bacterium Isolated from a Hot Spring Microbial Mat

Two closely related, aerobic, Gram- stain-negative, motile, oval-shaped, non- endospore-forming, moderately thermophilic bacteria, designated strains SYSU G05006T and SYSU G05005, were isolated from a bioreactor enrichment and the original sample was collected from Rehai National Park, Tengchong, Yunnan Province, PR China. The results of phylogenetic analy-sis based on the 16S rRNA gene sequences indicated that these two strains were closely related to Caldovatus sediminis YIM 72346T (96.75 and 96.89 % sequence similarity, respectively). The whole genome size of strain SYSU G05006T was 3.87 Mbp with a DNA G+C content of 75.33 mol%. The average nucleotide identity (ANI based on the MUMmer algorithm <= 90.31 % and ANI based on B iota asT <= 89.36 %) and digital DNA-DNA hybridization (<= 35.10 %) values between strain SYSU G05006T and other members of the family Acetobacteraceae were all lower than the threshold values recommended for distinguish-ing novel prokaryotic species. Optimal growth of the strain was observed at 55 degrees C and pH 6.0. Ubiquinone- 10 was the predominant respiratory lipoquinone. The major cellular fatty acids included iso-C14 : 0, C16 : 1 omega 5c, summed feature 5 and summed feature 7. The major polar lipids consisted of diphosphatidylglycerol, one unidentified aminolipid, phosphatidylg-lycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified phospholipids and two unidentified lipids. Based on results of phylogenetic analyses, comparative genomics and phenotypic characteristics, we describe a new species of the genus Caldovatus represented by strain SYSU G05006T (=KCTC 82831T=MCCC 1K06125T), for which we propose the name Caldovatus aquaticus sp. nov.