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

Strains 1-1N(T) and GYSZ_1(T) 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(T) was non-motile, whereas strain GYSZ_1(T) was motile by means of one polar flagellum. The temperature, pH and salinity concentration ranges for growth of 1-1N(T) were 10-45 degrees C (optimum 30 degrees C), pH 5.5-8.0 (optimum 7.0) and 0-90 gl(-1 )NaCl (optimum 50 gl(-1)). while the growth of GYSZ_1(T) occurred at 4-45 degrees C (optimum 33 degrees C), pH 5.0-8.5 (optimum 6.5) and 5-90 gl(-1) NaCl (optimum 20 gl(-1)). 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(T) were C-16:1 omega 7c, C-16:0, C-18:1 omega 7c and C-18:0, while the predominant fatty acids of strain GYSZ_1(T) were C-16:0, omega 7c C-16:0, C-18:2 omega 7c and C-14:0 3-OH. The DNA G+C contents of 1-1N(T) and GYSZ_1(T) were 34.5 mol% and 33.2 mot%, respectively. Phylogenetic analysis based on 16S rRNA, gene sequences indicated that 1-1N(T) and GYSZ_1(T) represented members of the genus Sulfurimonas, with the highest sequence similarities to Sulfurimonas crateris SN118(T) (97.4%) and Sulfurimonas denitrificans DSM 1251(T) (94.7%), respectively. However, 1-1N(T) and GYSZ_1(T) shared 95.5% similarity of 16S rRNA gene sequences, representing different species of the genus Sulfurimonas. On the basis of the physiological properties and the results of phylogenetic analyses, including average nucleotide identity and in silico DNA-DNA hybridization values, strains 1-1N(T) and GYSZ_1(T) represent two novel species within the genus Sulfurimonas, for which the names Sulfurimonas xiamenensis sp. nov. and Sulfurimonas lithotrophica sp. nov. are proposed, with the type strains 1-1N(T) (=MCCC 1A14514(T)=KCIC 15851(T)) and GYSZ_1(T) (=MCCC 1A14739(T) =KCTC 15853(T)), respectively. Our results also justify an emended description of the genus Sulfurimonas.