sp. nov. and sp. nov., hydrogen- and sulfur-oxidizing chemolithoautotrophs within the isolated from coastal sediments, and an emended description of the genus .

Strains 1-1N and GYSZ_1 were isolated from marine sediments collected from the coast of Xiamen, PR China. Cells of the two strains were Gram-stain-negative, rod-shaped or slightly curved. Strain 1-1N was non-motile, whereas strain GYSZ_1 was motile by means of one polar flagellum. The temperature, pH and salinity concentration ranges for growth of 1-1N were 10-45 °C (optimum 30 °C), pH 5.5-8.0 (optimum 7.0) and 0-90 g l NaCl (optimum 50 g l), while the growth of GYSZ_1 occurred at 4-45 °C (optimum 33 °C), pH 5.0-8.5 (optimum 6.5) and 5-90 g l NaCl (optimum 20 g l). The two novel isolates were obligate chemolithoautotrophs capable of growth using hydrogen, thiosulfate, sulfide or elemental sulfur as the sole energy source, and nitrate, elemental sulfur or molecular oxygen as an electron acceptor. The major fatty acids of 1-1N were Cω, C, Cω and C, while the predominant fatty acids of strain GYSZ_1 were Cω, C, Cω7 and C 3-OH. The DNA G+C contents of 1-1N and GYSZ_1 were 34.5 mol% and 33.2 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that 1-1N and GYSZ_1 represented members of the genus , with the highest sequence similarities to SN118 (97.4 %) and DSM 1251 (94.7 %), respectively. However, 1-1N and GYSZ_1 shared 95.5 % similarity of 16S rRNA gene sequences, representing different species of the genus . On the basis of the physiological properties and the results of phylogenetic analyses, including average nucleotide identity and DNA-DNA hybridization values, strains 1-1N and GYSZ_1 represent two novel species within the genus , for which the names sp. nov. and sp. nov. are proposed, with the type strains 1-1N (=MCCC 1A14514=KCTC 15851) and GYSZ_1 (=MCCC 1A14739=KCTC 15853), respectively. Our results also justify an emended description of the genus .