title: Desulfurella kamchatkensis sp. nov. and desulfurella propionica sp. nov., new sulfur-respiring thermophilic bacteria from Kamchatka thermal environments.
abstract: Two strains of moderately thermophilic bacteria, which reduce elemental sulfur to hydrogen sulfide, were isolated from volcanic sources in Kamchatka. Strain K-119T was obtained from a thermophilic microbial community associated with Thermothrix thiopara, and strain U-8T was isolated from a cyanobacterial mat inhabiting a sulfide-rich hot spring. Cells of both strains are short Gram-negative rods, motile with one polar flagellum (strain K-119T) or non-motile (strain U-8T). Both strains are obligate anaerobes, have temperature otima of 54-55 degrees C and pH optima of 6.9-7.2. Molecular hydrogen, acetate, fumarate, malate, pyruvate, lactate and long-chain saturated fatty acids served as growth substrates for both species; strain U-8T was also able to grow on propionate. All substrates were oxidized completely, H2S and CO2 being the only metabolic products. Elemental sulfur was obligately required for growth of strain K-119T, whereas strain U-8T was able to grow also with thiosulfate as electron acceptor and on pyruvate without an external electron acceptor. The DNA G + C contents of strains K-119T and U-8T were 31.6 and 32.2 mol%, respectively. Phenotypic features and the results of 16S rRNA sequencing indicate the affiliation of the new isolates to the genus Desulfurella. The DNA-DNA hybridization with Desulfurella acetivorans was 40% for strain K-119T and 55% for strain U-8T; the DNA-DNA hybridization between the new isolates was 32%. Based on the results of morphological, physiological and phylogenetic studies the following two new species are proposed: Desulfurella kamchatkensis sp. nov. with the type strain K-119T (= DSM 10409T) and Desulfurella propionica sp. nov. with the type strain U-8T (= DSM 10410T).
authors.affiliation: Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia. mir@imbran.msk.su
authors.forename: M L
authors.initials: ML
authors.lastname: Miroshnichenko
authors.forename: F A
authors.initials: FA
authors.lastname: Rainey
authors.forename: H
authors.initials: H
authors.lastname: Hippe
authors.forename: N A
authors.initials: NA
authors.lastname: Chernyh
authors.forename: N A
authors.initials: NA
authors.lastname: Kostrikina
authors.forename: E A
authors.initials: EA
authors.lastname: Bonch-Osmolovskaya
mesh_terms: D004269:DNA, Bacterial / Q000032:analysis; D016965:Gram-Negative Anaerobic Straight, Curved, and Helical Rods / Q000145:classification* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012426:Russia; D017423:Sequence Analysis, RNA; D016999:Sulfur-Reducing Bacteria / Q000145:classification* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure
chemical_list: D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S