Ciceribacter thiooxidans sp. nov., a novel nitrate-reducing thiosulfate-oxidizing bacterium isolated from...

Two facultative chemolithotrophic, nitrate-reducing thiosulfate-oxidizing strains, F43b^T and F21, were isolated from the sulfide-rich anoxic sediment of an urban creek in Pearl River Delta, China. Both strains were Gram-negative, facultatively anaerobic, non-spore-forming and rod-shaped with a flagellum. Phylogenetic analyses of 16S rRNA genes and the thrC, recA, glnII and atpD housekeeping genes revealed that the type strain shared high sequence similarities to Ciceribacter lividus MSSRFBL1^T, with 98.8, 90.9, 94.8, 95.4 and 96.1 % identity, respectively. In addition, the major isoprenoid quinone (ubiquinone Q-10) and the DNA G+C content (66.0 mol%) of the type strain were similar to those of Ciceribacter lividus MSSRFBL1^T. These results strongly support the classification of strains F43b^T and F21 into the genus Ciceribacter. However, these strains diverged markedly from strain MSSRFBL1^T with respect to several physiological and biochemical properties such as their semi-translucent colonies and nitrate-reducing and simultaneous thiosulfate-oxidizing respiration. Furthermore, the predominant fatty acids of strain F43b^T were summed feature 2 (C18 : 1ω9t and/or C18 : 1ω9c and/or C18 : 1ω11t), C14 : 0 3-OH, C18 : 0 and C16 : 0, and its polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidymonomethylethanolamine and an unidentified glycolipid, which represented another two significant differences from strain MSSRFBL1^T. Importantly, the DNA-DNA relatedness between strain F43b^T and MSSRFBL1^T was only 47.7 %. Based on the aforementioned polyphasic taxonomic results, the two isolates are suggested to represent a novel species of the genus Ciceribacter, for which the name Ciceribacterthiooxidans sp. nov. is proposed; the type strain is F43b^T (=CCTCC AB 2016062^T=KCTC 52231^T).