Description of Anaerotignum aminivorans gen. nov., sp. nov., a strictly anaerobic, amino-acid-decomposing bacterium isolated from a methanogenic reactor, and reclassification of Clostridium propionicum, Clostridium neopropionicum and Clostridium lactatifermentans as species of the genus Anaerotignum.

A strictly anaerobic bacterial strain (SH021T) was isolated from a methanogenic reactor. Cells were Gram-stain-positive, motile, straight or slightly curved rods. The optimum temperature for growth was 35 °C, and the optimum pH was 6.1-7.7. The strain was asaccharolytic and utilized amino acids as growth substrates. The strain produced acetate and propionate from l-alanine and l-serine, and propionate and butyrate from l-threonine. Branched-chain amino acids (l-isoleucine, l-leucine and l-valine) were utilized weakly, and isovalerate or isobutyrate was produced. Strain SH021T utilized pyruvate and lactate, and converted them to acetate and propionate. The genomic DNA G+C content was 38.2 mol%. Compounds related to iso-C15 : 0 were detected as major components in the cellular fatty acids analysis. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. On the basis of 16S rRNA gene sequences, the most closely related known species were Clostridium propionicum, Clostridium neopropionicum and Clostridium lactatifermentans in cluster XIVb of the class Clostridia. Based on the phylogenetic and phenotypic data, Anaerotignum aminivorans gen. nov., sp. nov. is proposed to accommodate strain SH021T (=JCM 31556T=DSM 103575T). For the three related species of the genus Clostridium, Anaerotignum propionicum comb. nov. (type strain DSM 1682T=JCM 1430T=ATCC 25522T=CCUG 9280T=NCIMB 10656T=VPI 5303T), Anaerotignum neopropionicum comb. nov. (type strain X4T=DSM 3847T=KCTC 15564T) and Anaerotignum lactatifermentans comb. nov. (type strain G17T=DSM 14214T=LMG 20954T) are proposed with emended descriptions of these species.

Descriptions of Anaerotaenia torta gen. nov., sp. nov. and Anaerocolumna cellulosilytica gen. nov., sp. nov. isolated from a methanogenic reactor of cattle waste and reclassification of Clostridium aminovalericum, Clostridium jejuense and Clostridium xylanovorans as Anaerocolumna species.

Strictly anaerobic bacterial strains (FH052T and SN021T) belonging to clostridial cluster XIVa were isolated from a methanogenic reactor. Cells of the two strains were Gram-stain-positive, slender or curved rods producing terminal spores. The strains were slightly alkaliphilic. They fermented various carbohydrates including xylan and produced acetate, ethanol and H2. Strain SN021T decomposed cellulose. The genomic DNA G+C contents were 47.2 mol% for strain FH052T and 38.1 mol% for strain SN021T. The two strains had common cellular fatty acids such as C16 : 0, C16 : 0 dimethylacetal and C18 : 1ω7c dimethylacetal as major components. 16S rRNA gene sequence similarity between the two strains was 94.3 % and they shared closely related species such as Clostridium jejuense, Clostridium xylanovorans and Clostridium aminovalericum (92.6-95.7 % sequence similarity). Phenotypic and phylogenetic analyses suggested that these two isolates should be assigned to novel genera other than the genus Clostridium, and thus the genera Anaerotaenia gen. nov. and Anaerocolumna gen. nov. in the family Lachnospiraceae were proposed to accommodate them as Anaerotaenia torta gen. nov., sp. nov. for strain FH052T (=JCM 30820T=DSM 100431T) and Anaerocolumna cellulosilytica gen. nov., sp. nov. for strain SN021T (=JCM 30819T=DSM 100423T). For the three related Clostridium species, Anaerocolumna aminovalerica DSM 1283T (=JCM 11016T=ATCC 13725T) comb. nov., Anaerocolumna jejuensis HY-35-12T (=DSM 15929T=KCTC 5026T) comb. nov. and Anaerocolumna xylanovoransstrain HESP1T (=DSM 12503T=JCM 31057T) comb. nov. are proposed with emended descriptions of these species.

Description of Propionispira arcuata sp. nov., isolated from a methanogenic reactor of cattle waste, reclassification of Zymophilus raffinosivorans and Zymophilus paucivorans as Propionispira raffinosivorans comb. nov. and Propionispira paucivorans comb. nov. and emended description of the genus Propionispira.

A strictly anaerobic bacterial strain, WK011(T), was isolated from a methanogenic reactor treating waste from cattle farms. The cells stained Gram-negative and were curved rods with a polar or subpolar flagellum. Spore formation was not observed. The optimum temperature for growth was 35 °C and the optimum pH was 6.7. Tests for oxidase, catalase and nitrate-reduction activities were negative. Hydrogen sulfide was produced. The strain fermented carbohydrates and produced acetate and propionate as major fermentation products. The genomic DNA G+C content was 41.7 mol%. The major cellular fatty acids were C15:0, C16:1ω9c and C18:1 dimethylacetal. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. The most closely related species to strain WK011(T) on the basis of 16S rRNA gene sequences were Propionispira arboris and Zymophilus raffinosivorans (95.6% sequence similarity to the type strains of both species). It was shown by phylogenetic and phenotypic examination of the type strains of related species, including the second species of the genus Zymophilus, Zymophilus paucivorans, that the two genera should be combined and that the two species of the genus Zymophilus should be transferred to the genus Propionispira, as Propionispira raffinosivorans comb. nov. (type strain SH2(T) = ATCC 49691(T) = DSM 20765(T)) and Propionispira paucivorans comb. nov. (type strain AA1(T) = ATCC 49689(T) = DSM 20756(T)), with an emended description of the genus Propionispira. Based on differences in the phylogenetic and phenotypic characteristics of strain WK011(T) from those of closely related species, the novel species Propionispira arcuata sp. nov. is proposed to accommodate the strain. The type strain is WK011(T) ( = JCM 16475(T) = DSM 22929(T)).

Anaerocella delicata gen. nov., sp. nov., a strictly anaerobic bacterium in the phylum Bacteroidetes isolated from a methanogenic reactor of cattle farms.

A strictly anaerobic bacterial strain (WN081(T)) was isolated from rice-straw residue in a methanogenic reactor treating waste from cattle farms in Japan. Cells were Gram-staining negative, non-motile, non-spore-forming straight rods. The strain grew rather well on PY agar slants supplemented with a B-vitamin mixture as well as sugars (PYV4S medium) and made translucent and glossy colonies. Growth in liquid medium with the same composition, however, was scanty, and growth was not improved in spite of various additives to the medium. Strain WN081(T) produced small amounts of acetate, propionate, isobutyrate, butyrate, isovalerate and H(2) from PYV liquid medium. The strain did not use carbohydrates or organic acids. The pH range for growth was narrow (pH 6.8-8.2), having a pH optimum at 6.8-7.5. The temperature range for growth was 10-37°C, the optimum being 25-30°C. The strain was sensitive to bile, and did not have catalase or oxidase activities. Hydrogen sulfide was produced from L-cysteine and L-methionine as well as peptone. Indole was produced from L-tryptophan and peptone. The strain had iso-C(15:0) as the exclusively predominant cellular fatty acid (70%) together with some branched chain components (such as iso-C(15:0) DMA, iso-C(17:0) 3-OH and iso-C(15:0) aldehyde) as minor components. The genomic DNA G+C content was 32.3 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence placed strain WN081(T) in the phylum Bacteroidetes with rather low sequence similarities with the related species such as Rikenella microfusus (85.7% sequence similarity), Alistipes putredinis (85.5%) and Alistipes finegoldii (85.5%) in the family Rikenellaceae. Based on the phylogenetic, physiological and chemotaxonomic analyses, the novel genus and species Anaerocella delicata gen. nov., sp. nov. is proposed to accommodate the strain. The type strain is WN081(T) (= JCM 17049(T) = DSM 23595(T)).

Bacteroides paurosaccharolyticus sp. nov., isolated from a methanogenic reactor treating waste from cattle farms.

A strictly anaerobic bacterial strain (WK042(T)) was isolated from rice-straw residue in a methanogenic reactor treating waste from cattle farms in Japan. Cells were Gram-staining-negative, non-motile, non-spore-forming rods. Growth was stimulated well by haemin, and was enhanced by cobalamin (vitamin B(12)). Strain WK042(T) utilized arabinose, xylose, glucose, mannose and aesculin as preferred substrates. Maltose, dextrin, glycogen, starch and pectin were also utilized, although growth on these substrates was much slower. The strain produced acetate, propionate and succinate from these saccharides. The strain was slightly alkaliphilic, with optimum growth at pH 7.7. The temperature range for growth was 10-40 °C, the optimum being 35 °C. The strain was sensitive to bile. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(17 : 0) 3-OH and C(15 : 0). Menaquinone 11 (MK-11) was the major respiratory quinone and the genomic DNA G+C content was 41.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences placed the strain in the phylum Bacteroidetes. Strain WK042(T) was related distantly to the type strains of species in the cluster including Bacteroides massiliensis, Bacteroides vulgatus and Bacteroides dorei (91-92 % 16S rRNA gene sequence similarity). Based on data from the present phylogenetic, physiological and chemotaxonomic analyses, strain WK042(T) is considered to represent a novel species of the genus Bacteroides, for which the name Bacteroides paurosaccharolyticus sp. nov. is proposed. The type strain is WK042(T) (=JCM 15092(T) =DSM 21004(T)).

Desulfovibrio butyratiphilus sp. nov., a Gram-negative, butyrate-oxidizing, sulfate-reducing bacterium isolated from an anaerobic municipal sewage sludge digester.

Strictly anaerobic, mesophilic, sulfate-reducing bacterial strains were isolated from two anaerobic municipal sewage sludge digesters. One representative strain (BSY(T)) was characterized phenotypically and phylogenetically. Cells were Gram-negative, motile by means of a single polar flagellum, non-spore-forming, curved rods. Cells had desulfoviridin and cytochrome type c. Catalase and oxidase activities were not detected. The optimum NaCl concentration for growth was 0.5 % (w/v). The optimum temperature was 35 degrees C and the optimum pH was 7.1. Strain BSY(T) utilized butyrate, 2-methylbutyrate, valerate, pyruvate, lactate, ethanol, 1-propanol, butanol and H(2) as electron donors for sulfate reduction. This strain grew lithoautotrophically with H(2)/CO(2) under sulfate-reducing conditions. Most organic electron donors were incompletely oxidized to mainly acetate, whereas 2-methylbutyrate and valerate were oxidized to equivalent amounts of acetate and propionate. Strain BSY(T) utilized thiosulfate as an electron acceptor, and grew with pyruvate in the absence of electron acceptors. The genomic DNA G+C content of strain BSY(T) was 63.3 mol%. Menaquinone MK-6(H(2)) was the major respiratory quinone. Major cellular fatty acids were C(14 : 0), C(16 : 0), C(16 : 1) omega7 and C(18 : 1)omega7. Phylogenetic analyses based on 16S rRNA and dissimilatory sulfite-reductase beta-subunit gene sequences assigned strain BSY(T) to the genus Desulfovibrio in the family Desulfovibrionaceae within the class Deltaproteobacteria . Its closest recognized relative based on 16S rRNA gene sequences was the type strain of Desulfovibrio putealis (95.3 % similarity). On the basis of significant differences in 16S rRNA gene sequences and phenotypic characteristics, the sewage sludge strains are considered to represent a single novel species of the genus Desulfovibrio, for which the name Desulfovibrio butyratiphilus sp. nov. is proposed. The type strain is BSY(T) (=JCM 15519(T)=DSM 21556(T)).