The genus Desulfotomaculum is a heterogeneous group of spore-forming sulfate-reducing bacteria. The type species of the genus is Desulfotomaculum nigrificans (Approved Lists 1980) emend. Visser et al. 2014. The results of phylogenetic analysis demonstrated that the genus Desulfotomaculum already has lost the clustering monophyly and was segregated into some distinct groups with low sequence similarity. Major features of the type strains in these groups were compared, and four novel genera, Desulfallas gen. nov., Desulfofundulus gen. nov., Desulfofarcimen gen. nov. and Desulfohalotomaculum gen. nov. were proposed to accommodate species transferred from the genus Desulfotomaculum .

In previous studies, two hydrocarbon-degrading sulfate-reducing bacteria, strains PP31T and PL12T, were obtained from oil-polluted marine sediments of Shuaiba, Kuwait. They had been reported as organisms capable of anaerobic degradation of p-xylene and n-alkanes, respectively. The 16S rRNA gene sequence of strain PP31T showed 98.8 % sequence similarities to that of Desulfosarcina variabilis ‘Montpellier’T. Strains PL12T had 97.8 % of sequence similarity to Desulfosarcina ovata oXys1T. They both have been partially characterized, but not been validly published as new species of the genus Desulfosarcina . In this study, additional characterizations of these strains were made to describe them as two new species of the genus Desulfosarcina . Major cellular fatty acids of strain PP31T were C15 : 0 (25.9 %) and anteiso-C15 : 0 (22.3 %), whereas those of strain PL12T were C15 : 0 (21.3 %), C16 : 0 (17.8 %) and anteiso-15 : 0 (11.6 %). The phylogenetic tree based on 16S rRNA gene revealed that these isolates should not be classified as any of the known species in the genus Desulfosarcina . On the basis of phenotypic and phylogenetic analyses, these two sulfate reducers are proposed to form two novel species of the genus Desulfosarcina : Desulfosarcina widdelii sp. nov. (PP31T=JCM 31729T=DSM 103921T) and Desulfosarcina alkanivorans sp. nov. (PL12T=JCM 31728T=DSM 103901T). In addition, emended description of the genus Desulfosarcina is presented in this study.

A novel sulfate-reducing bacterium, strain S28bF^T, was isolated from tidal flat sediment from Tokyo Bay, Japan. Cells of strain S28bF^T were rod-shaped (0.5–0.6×1.7–3.8 µm), motile and Gram-stain-negative. For growth, the optimum pH was pH 6.8–7.3 and the optimum temperature was 34–42 °C. Strain S28bF^T used sulfate and thiosulfate as electron acceptors, but not nitrate. The G+C content of the genomic DNA was 56.6 mol%. The fatty acid profile of strain S28bF^T was characterized by the presence of anteiso-C_15 : 0 and C_16 : 0 as the major components. Phylogenetic analyses based on genes for 16S rRNA, the alpha subunit of dissimilatory sulfite reductase (dsrA) and adenosine-5′-phosphosulfate reductase (aprA) revealed that the isolated strain belonged to the class Deltaproteobacteria . Its closest relative was Desulfosarcina cetonica DSM 7267^T with a 16S rRNA gene sequence similarity of 93.3 %. Two other strains, S28OL1 and S28OL2 were also isolated from the same sediment. These strains were closely related to S28bF^T with 16S rRNA gene sequence similarities of 99 %, and the same physiological characteristics were shared with strain S28bF^T. On the basis of phylogenetic and phenotypic characterization, a novel species in a new genus, Desulfatitalea tepidiphila gen. nov., sp. nov., is proposed to accommodate the strains obtained in this study. The type strain is S28bF^T ( = NBRC 107166^T = DSM 23472^T).

A novel facultatively anaerobic bacterium, strain HC45^T, was isolated from sediment of a brackish meromictic lake in Japan, Lake Harutori. Cells were pleomorphic, and filamentous bodies were 5–100 μm in length. For growth, the optimum pH was 7.0 and the optimum temperature was 45–50 °C. The G+C content of the genomic DNA was 71 mol%. iso-C_15 : 0and anteiso-C_15 : 0were the major components in the cellular fatty acid profile. The predominant respiratory quinone was MK-7. Strain HC45^Tshared very low 16S rRNA gene sequence similarity with cultivated strains ( ≤ 85 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was distantly related to members of the familySymbiobacteriaceaeand family XVIIIncertae Sedisin the classClostridia, and they formed a cluster separate from canonical species of the phylumFirmicutes. These results indicated that strain HC45^Tshould not be placed in any existing class of the phylumFirmicutes. On the basis of phylogenetic and phenotypic characterization,Limnochorda pilosagen. nov., sp. nov. is proposed with HC45^T( = NBRC 110152^T = DSM 28787^T) as the type strain, as the first representative of novel taxa,Limnochordalesord. nov.,Limnochordaceaefam. nov. inLimnochordiaclassis. nov.

A novel strictly anaerobic chemoorganotrophic bacterium, designated Mahy22^T, was isolated from sulfidic bottom water of a shallow brackish meromictic lake in Japan. Cells of the strain were Gram-stain-negative, non-motile and coccoid in shape with diameters of about 600–800 nm. The temperature range for growth was 15–37 °C, with optimum growth at 30–32 °C. The pH range for growth was pH 6.2–8.9, with optimum growth at pH 7.2–7.4. The strain grew with NaCl concentrations of 5% or below (optimum, 2–3%). Growth of the strain was enhanced by the addition of thiosulfate. The major cellular fatty acids were C_16:0 and anteiso-C_15:0. Respiratory quinones were not detected. The complete genome sequence of strain Mahy22^T possessed a 1 885 846 bp circular chromosome and a 12 782 bp circular genetic element. The G+C content of the genome sequence was 30.1 mol%. Phylogenetic analysis based on the 16S rRNA gene revealed that the novel strain belonged to the family Acholeplasmataceae , class Mollicutes . The closest relative of strain Mahy22^T with a validly published name was Acholeplasma palmae J233^T with a 16S rRNA gene sequence similarity of 90.5%. Based on the results of polyphasic analysis, the name Mariniplasma anaerobium gen. nov., sp. nov. is proposed to accommodate strain Mahy22^T, along with reclassification of some Acholeplasma species into Alteracholeplasma gen. nov., Haploplasma gen. nov. and Paracholeplasma gen. nov.

A novel aerobic bacterial strain P3T was isolated from a red snow obtained from coastal Antarctic. Cells of strain P3T were rod-shaped, non-motile, catalase-negative, oxidase-positive, and Gram-stain-negative. Growth was observed at temperatures ranging from 0 to 25°C, and the optimum growth was observed at 15°C. The range of pH for growth was 5.3-7.8. The G+C content of genomic DNA was 55.0 mol%. The major components in fatty acid profile were iso-C15:0, summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 anteiso-C15:0, and summed feature 3 (iso-C16:17c and/or iso-C16:16c). The predominant isoprenoid quinone was MK-7. Phylogenetic analysis based on 16S rRNA gene sequence indicated that the novel isolate was a member of the genus Hymenobacter, and the strain showed highest sequence similarity (94%) with H. glaciei VUG-A130T, H. soli PB17T, and H. antarcticus VUG-A42aaT. On the basis of its phylogenetic and phenotypic properties, strain P3T (=DSM 101755T = NBRC 111535 T) is proposed as the type strain of a new species, Hymenobacter nivis sp. nov.