Description of Oceanispirochaeta crateris sp. nov. and reclassification of Spirochaeta perfilievii as Thiospirochaeta perfilievii gen. nov., comb. nov.

A novel obligately anaerobic spirochete strain K2T was isolated from bottom marine sediments at Crater Bay of Yankicha Island (Kuril Islands, Russia). Strain K2T had helical shape and Gram-negatively stained. The optimal growth conditions were as follows: the optimum temperature was 28-30 °C with range 5-34 °C; optimal pH at 7.0-7.5 with range of 6.8-8.5; NaCl optimum at 3-3.5 % (w/v) and range of 1-7 % (w/v). Strain K2T was catalase- and oxidase-negative. Glucose fermentation products were acetate, lactate, ethanol, CO2, H2. The major fatty acids were C14 : 0, iso-C13 : 0, iso-C15:0, C14 : 0 DMA, iso-C15 : 0 DMA. The G+C content of genomic DNA was 43.2 mol%. Phylogenetic analyses of 16S rRNA genes showed that strain K2T belonged to the genus Oceanispirochaeta of the family Spirochaetaceae. The 16S rRNA gene sequence similarity of strain K2T and O. litoralis DSM 2029T and O. sediminicola DSM 104770T was 96 and 94 %, respectively. Based on the results of our study, we propose the name Oceanispirochaeta crateris sp. nov.; type strain K2T (=DSM 16308T=VKM B-3266T). Also, the taxonomic status of Spirochaeta perfilevii was revised: 16S rRNA genes sequence showed less than 89 % similarity to nearest phylogenetic neighbours. Therefore, we proposed to separate this species into a novel genus Thiospirochaeta - T. perfilievii gen. nov., comb. nov.

Complete Genome Sequences and Methylome Analysis of Two Environmental Spirochaetes.

Here, we report the finished closed genomes of two environmental bacteria, Oceanispirochaeta crateria K2 and Thiospirochaeta perfilievii P (formally known as Spirochaeta perfilievii P). In addition, we provide methylation data and the associated enzymes predicted and confirmed to be responsible for each modified motif.

Spirochaeta perfilievii sp. nov., an oxygen-tolerant, sulfide-oxidizing, sulfur- and thiosulfate-reducing spirochaete isolated from a saline spring.

A novel strain of fermenting, aerotolerant, chemo-organoheterotrophic spirochaete designated P(T) was isolated from a sulfur 'Thiodendron' mat in a saline spring at the Staraya Russa resort (Novgorod Region, Russia). Cells of strain P(T) exhibited a helical shape. The spirochaete required sulfide in the growth medium and was able to oxidize it non-enzymically to elemental sulfur via the interaction of H(2)O(2) with sulfide and deposit it in the periplasmic space. Growth occurred at 4-32 °C (optimum at 28-30 °C), pH 6.0-8.5 (optimum pH 7.0-7.5), and in 0.1-1 M NaCl (optimum 0.35 M). The isolate used several sugars and polysaccharides as carbon or energy sources but did not use peptides, amino acids, organic acids or alcohols. The products of glucose fermentation were formate, acetate, ethanol, pyruvate, CO(2) and H(2). The genomic DNA G+C content was 41.7 mol%. 16S rRNA gene sequence analysis showed that strain P(T) fell within a group of species in the genus Spirochaeta, including Spirochaeta litoralis, S. isovalerica and S. cellobiosiphila, with which it shared less then 89 % sequence similarity. On the basis of its morphology, physiology and other phenotypic properties, as well as its phylogenetic position, the new isolate is considered to represent a novel species of the genus Spirochaeta, for which the name Spirochaeta perfilievii sp. nov. is proposed. The type strain is P(T) (=DSM 19205(T) =VKM B-2514(T)).