Showing papers in "International Journal of Systematic and Evolutionary Microbiology in 2011"
TL;DR: Phenotypically, strains AR4(T), SOP9 and LAY were most similar to Methylocella species, but differed from members of this genus by cell morphology, greater tolerance of low pH, detectable activities of RuBP pathway enzymes and inability to grow on multicarbon compounds.
Abstract: Two strains of aerobic methanotrophic bacteria, AR4T and SOP9, were isolated from acidic (pH 3.8–4.0) Sphagnum peat bogs in Russia. Another phenotypically similar isolate, strain LAY, was obtained from an acidic (pH 4.0) forest soil in Germany. Cells of these strains were Gram-negative, non-pigmented, non-motile, thin rods that multiplied by irregular cell division and formed rosettes or amorphous cell conglomerates. Similar to Methylocella species, strains AR4T, SOP9 and LAY possessed only a soluble form of methane monooxygenase (sMMO) and lacked intracytoplasmic membranes. Growth occurred only on methane and methanol; the latter was the preferred growth substrate. mRNA transcripts of sMMO were detectable in cells when either methane or both methane and methanol were available. Carbon was assimilated via the serine and ribulose-bisphosphate (RuBP) pathways; nitrogen was fixed via an oxygen-sensitive nitrogenase. Strains AR4T, SOP9 and LAY were moderately acidophilic, mesophilic organisms capable of growth between pH 3.5 and 7.2 (optimum pH 4.8–5.2) and at 4–33 °C (optimum 20–23 °C). The major cellular fatty acid was 18 : 1ω7c and the quinone was Q-10. The DNA G+C content was 55.6–57.5 mol%. The isolates belonged to the family Beijerinckiaceae of the class Alphaproteobacteria and were most closely related to the sMMO-possessing methanotrophs of the genus Methylocella (96.4–97.0 % 16S rRNA gene sequence similarity), particulate MMO (pMMO)-possessing methanotrophs of the genus Methylocapsa (96.1–97.0 %), facultative methylotrophs of the genus Methylovirgula (96.1–96.3 %) and non-methanotrophic organotrophs of the genus Beijerinckia (96.5–97.0 %). Phenotypically, strains AR4T, SOP9 and LAY were most similar to Methylocella species, but differed from members of this genus by cell morphology, greater tolerance of low pH, detectable activities of RuBP pathway enzymes and inability to grow on multicarbon compounds. Therefore, we propose a novel genus and species, Methyloferula stellata gen. nov., sp. nov., to accommodate strains AR4T, SOP9 and LAY. Strain AR4T ( = DSM 22108T = LMG 25277T = VKM B-2543T) is the type strain of Methyloferula stellata.
237 citations
TL;DR: The ability of a group of Bacillus strains closely related to strain FZB42(T) to colonize Arabidopsis roots is demonstrated and two novel subspecies are proposed, designated B. amyloliquefaciens subsp.
Abstract: The whole-genome-sequenced rhizobacterium Bacillus amyloliquefaciens FZB42T (Chen et al., 2007) and other plant-associated strains of the genus Bacillus described as belonging to the species Bacillus amyloliquefaciens or Bacillus subtilis are used commercially to promote the growth and improve the health of crop plants. Previous investigations revealed that a group of strains represented a distinct ecotype related to B. amyloliquefaciens; however, the exact taxonomic position of this group remains elusive (Reva et al., 2004). In the present study, we demonstrated the ability of a group of Bacillus strains closely related to strain FZB42T to colonize Arabidopsis roots. On the basis of their phenotypic traits, the strains were similar to Bacillus amyloliquefaciens DSM 7T but differed considerably from this type strain in the DNA sequences of genes encoding 16S rRNA, gyrase subunit A (gyrA) and histidine kinase (cheA). Phylogenetic analysis performed with partial 16S rRNA, gyrA and cheA gene sequences revealed that the plant-associated strains of the genus Bacillus, including strain FZB42T, formed a lineage, which could be distinguished from the cluster of strains closely related to B. amyloliquefaciens DSM 7T. DNA–DNA hybridizations (DDH) performed with genomic DNA from strains DSM 7T and FZB42T yielded relatedness values of 63.7–71.2 %. Several methods of genomic analysis, such as direct whole-genome comparison, digital DDH and microarray-based comparative genomichybridization (M-CGH) were used as complementary tests. The group of plant-associated strains could be distinguished from strain DSM 7T and the type strain of B. subtilis by differences in the potential to synthesize non-ribosomal lipopeptides and polyketides. Based on the differences found in the marker gene sequences and the whole genomes of these strains, we propose two novel subspecies, designated B. amyloliquefaciens subsp. plantarum subsp. nov., with the type strain FZB42T ( = DSM 23117T = BGSC 10A6T), and B. amyloliquefaciens subsp. amyloliquefaciens subsp. nov., with the type strain DSM 7T( = ATCC 23350T = Fukumoto Strain FT), for plant-associated and non-plant-associated representatives, respecitvely. This is in agreement with results of DDH and M-CGH tests and the MALDI-TOF MS of cellular components, all of which suggested that the ecovars represent two different subspecies.
230 citations
TL;DR: It is proposed that strain NEAU 119(T) represents a novel species, Actinoalloteichus nanshanensis sp.
Abstract: A Gram-positive, aerobic actinomycete, designated strain NEAU 119T, was isolated from the rhizosphere of a fig tree and was characterized using a polyphasic approach. The isolate formed branching, non-fragmenting vegetative hyphae and produced black pigment on yeast extract/malt extract (ISP medium 2). The G+C content of the DNA was 76.6 mol%. The organism had chemotaxonomic characteristics typical of the genus Actinoalloteichus and was closely related to the type strains of Actinoalloteichus cyanogriseus, Actinoalloteichus spitiensis and Actinoalloteichus hymeniacidonis, currently the only three recognized species of the genus Actinoalloteichus, sharing 16S rRNA gene similarities of 96.4, 96.6 and 98.1 %, respectively. However, the results of DNA–DNA hybridization studies demonstrated that the novel strain showed only 46.8 % relatedness with the type strain of A. hymeniacidonis. In addition, a set of phenotypic characteristics also readily distinguished strain NEAU 119T from the type strains of recognized species of the genus Actinoalloteichus. According to the above data, it is proposed that strain NEAU 119T represents a novel species, Actinoalloteichus nanshanensis sp. nov. The type strain of Actinoalloteichus nanshanensis is NEAU 119T ( = CGMCC 4.5714T = NBRC 106685T).
188 citations
TL;DR: The purpose of this report is to provide a description in accordance with the Rules of the Bacteriological Code (1990 Revision) and the correct name of this taxon, at the rank of subspecies, is Mycobacterium abscessus subsp.
Abstract: The names ‘Mycobacterium abscessus subsp. abscessus’ and ‘Mycobacterium abscessus subsp. massiliense’, proposed by Leao et al. (2009, J Clin Microbiol
47, 2691–2698), cannot be validly published. The purpose of this report is to provide a description in accordance with the Rules of the Bacteriological Code (1990 Revision). Moreover, the proposal of the name ‘Mycobacterium abscessus subsp. massiliense’ is contrary to Rule 38 and the correct name of this taxon, at the rank of subspecies, is Mycobacterium abscessus subsp. bolletii comb. nov. A description of Mycobacterium abscessus subsp. abscessus subsp. nov. and an emended description of Mycobacterium abscessus are also given.
183 citations
TL;DR: To the authors' knowledge, strain 6A8(T) is one of the most acidiphilic, hydrogenotrophic and salt-sensitive methanogens in pure culture and it is proposed that a new genus and species be established for this organism, Methanoregula boonei gen. nov.
Abstract: A novel acidiphilic, hydrogenotrophic methanogen, designated strain 6A8T, was isolated from an acidic (pH 4.0–4.5) and ombrotrophic (rain-fed) bog located near Ithaca, NY, USA. Cultures were dimorphic, containing thin rods (0.2–0.3 μm in diameter and 0.8–3.0 μm long) and irregular cocci (0.2–0.8 μm in diameter). The culture utilized H2/CO2 to produce methane but did not utilize formate, acetate, methanol, ethanol, 2-propanol, butanol or trimethylamine. Optimal growth conditions were near pH 5.1 and 35 °C. The culture grew in basal medium containing as little as 0.43 mM Na+ and growth was inhibited completely by 50 mM NaCl. To our knowledge, strain 6A8T is one of the most acidiphilic (lowest pH optimum) and salt-sensitive methanogens in pure culture. Acetate, coenzyme M, vitamins and yeast extract were required for growth. It is proposed that a new genus and species be established for this organism, Methanoregula boonei gen. nov., sp. nov. The type strain of Methanoregula boonei is 6A8T (=DSM 21154T =JCM 14090T).
165 citations
TL;DR: DNA-DNA hybridization results and some differentiating biochemical properties indicate that strain R26(T) represents a novel species, for which the name Elizabethkingia anophelis sp.
Abstract: The taxonomic position, growth characteristics and antibiotic resistance properties of a slightly yellow-pigmented bacterial strain, designated R26T, isolated from the midgut of the mosquito Anopheles gambiae, were studied. The isolate produced rod-shaped cells, which stained Gram-negative. The bacterium had two growth optima at 30–31 °C and 37 °C. Strain R26T demonstrated natural antibiotic resistance to ampicillin, chloramphenicol, kanamycin, streptomycin and tetracycline. 16S rRNA gene sequence analysis revealed that the isolate showed 98.6 % sequence similarity to that of Elizabethkingia meningoseptica ATCC 13253T and 98.2 % similarity to that of Elizabethkingia miricola GTC 862T. The major fatty acids of strain R26T were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 4 (iso-C15 : 0 2-OH and/or C16 : 1ω7c/t). Strain R26T contained only menaquinone MK-6 and showed a complex polar lipid profile consisting of diphosphatidylglycerol, phosphatidylinositol, an unknown phospholipid and unknown polar lipids and glycolipids. DNA–DNA hybridization experiments with E. meningoseptica CCUG 214T ( = ATCC 13253T) and E. miricola KCTC 12492T ( = GTC 862T) gave relatedness values of 34.5 % (reciprocal 41.5 %) and 35.0 % (reciprocal 25.7 %), respectively. DNA–DNA hybridization results and some differentiating biochemical properties indicate that strain R26T represents a novel species, for which the name Elizabethkingia anophelis sp. nov. is proposed. The type strain is R26T ( = CCUG 60038T = CCM 7804T).
157 citations
TL;DR: Three bacterial strains isolated from water samples taken at different locations in southern Sweden were studied to determine their taxonomic position using a polyphasic approach and represent a novel species of a new genus, for which the name Hydrotalea flava gen. nov. is proposed.
Abstract: Three bacterial strains, designated CCUG 51397T, CCUG 53736 and CCUG 53920, isolated from water samples taken at different locations in southern Sweden were studied to determine their taxonomic position using a polyphasic approach. Comparative analysis of 16S rRNA gene sequences showed that these bacteria had <93 % sequence similarity to all described species of the genera Sediminibacterium, Lacibacter, Flavihumibacter, Flavisolibacter, Niabella, Niastella, Segetibacter, Parasegetibacter, Terrimonas, Ferruginibacter, Filimonas and Chitinophaga. The three organisms grouped most closely with Sediminibacterium salmoneum NJ-44T but showed only 92.5 % sequence similarity to this strain, the only recognized species of this genus. The fatty acid profiles showed large amounts of iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G with smaller amounts of iso-C15 : 0 3-OH, iso-C16 : 0 3-OH and other fatty acids, which differentiated the novel strains from related genera. Biochemical tests performed on strains CCUG 51397T, CCUG 53736 and CCUG 53920 also gave different results from those of Sediminibacterium salmoneum NJ-44T and other related genera. Based on this evidence, strains CCUG 51397T, CCUG 53736 and CCUG 53920 represent a novel species of a new genus, for which the name Hydrotalea flava gen. nov., sp. nov. is proposed. The type strain of Hydrotalea flava is CCUG 51397T (=CCM 7760T). A formal allocation of the genera Sediminibacterium, Lacibacter, Flavihumibacter, Flavisolibacter, Niabella, Niastella, Segetibacter, Parasegetibacter, Terrimonas, Ferruginibacter, Filimonas and Chitinophaga to the family Chitinophagaceae fam. nov. is also proposed.
144 citations
TL;DR: The results of a study comparing the chemotaxonomic characteristics and phylogenetic positions of members of the genus Arcanobacterium indicated that the genus was not monophyletic and, therefore, was in need of taxonomic revision.
Abstract: The results of a study comparing the chemotaxonomic characteristics and phylogenetic positions of members of the genus Arcanobacterium indicated that the genus was not monophyletic and, therefore, was in need of taxonomic revision. Phylogenetically, the genus Arcanobacterium consisted of two distinct lines; a group comprising the species Arcanobacterium haemolyticum (the type species of the genus), A. hippocoleae, A. phocae and A. pluranimalium and a robust group consisting of the species A. abortisuis, A. bernardiae, A. bialowiezense, A. bonasi and A. pyogenes. On the basis of 16S rRNA signature nucleotide comparisons and menaquinone and phospholipid compositions, it is proposed that of these nine species only four, A. haemolyticum, A. hippocoleae, A. phocae and A. pluranimalium, should be affiliated with the genus Arcanobacterium and the species A. abortisuis, A. bernardiae, A. bialowiezense, A. bonasi and A. pyogenes should be reclassified as members of a new genus, Trueperella, as Trueperella abortisuis comb. nov., Trueperella bernardiae comb. nov., Trueperella bialowiezensis comb. nov., Trueperella bonasi comb. nov. and Trueperella pyogenes comb. nov. Positive results in Christie–Atkins–Munch-Petersen (CAMP) tests on A. haemolyticum, A. hippocoleae, A. phocae and A. pluranimalium also supported the rearrangement of the nine species in to separate genera. As such, an emended description of the genus Arcanobacterium is provided.
125 citations
TL;DR: A novel aerobic, chemoheterotrophic bacterium isolated from the rhizoplane of an aquatic plant (a reed, Phragmites australis) inhabiting a freshwater lake in Japan, was morphologically, physiologically and phylogenetically characterized.
Abstract: A novel aerobic, chemoheterotrophic bacterium, strain YO-36(T), isolated from the rhizoplane of an aquatic plant (a reed, Phragmites australis) inhabiting a freshwater lake in Japan, was morphologically, physiologically and phylogenetically characterized. Strain YO-36(T) was Gram-negative and ovoid to rod-shaped, and formed pinkish hard colonies on agar plates. Strain YO-36(T) grew at 20-40 °C with optimum growth at 30-35 °C, whilst no growth was observed at 15 °C or 45 °C. The pH range for growth was 5.5-8.5 with an optimum at pH 6.5. Strain YO-36(T) utilized a limited range of substrates, such as sucrose, gentiobiose, pectin, gellan gum and xanthan gum. The strain contained C(16 : 0), C(16 : 1), C(14 : 0) and C(15 : 0) as the major cellular fatty acids and menaquinone-12 as the respiratory quinone. The G+C content of the genomic DNA was 62.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YO-36(T) belonged to the candidate phylum OP10 comprised solely of environmental 16S rRNA gene clone sequences except for two strains, P488 and T49 isolated from geothermal soil in New Zealand; strain YO-36(T) showed less than 80 % sequence similarity to strains P488 and T47. Based on the phylogetic and phenotypic findings, a new genus and species, Armatimonas rosea gen. nov., sp. nov., is proposed for the isolate (type strain YO-36(T) = NBRC 105658(T) = DSM 23562(T)). In addition, a new bacterial phylum named Armatimonadetes phyl. nov. is proposed for the candidate phylum OP10 represented by A. rosea gen. nov., sp. nov. and Armatimonadaceae fam. nov., Armatimonadales ord. nov., and Armatimonadia classis nov.
118 citations
TL;DR: In this article, a novel facultatively autotrophic bacterium, designated strain sk43HT, was isolated from water of a freshwater lake in Japan and was found to be facultatively anaerobic.
Abstract: A novel facultatively autotrophic bacterium, designated strain sk43HT, was isolated from water of a freshwater lake in Japan. Cells of the isolate were curved rods, motile and Gram-reaction-negative. Strain sk43HT was facultatively anaerobic and autotrophic growth was observed only under anaerobic conditions. The isolate oxidized thiosulfate, elemental sulfur and hydrogen as sole energy sources for autotrophic growth and could utilize nitrate as an electron acceptor. Growth was observed at 8–32 °C (optimum 25 °C) and 6.4–7.6 (optimum pH 6.7–6.9). Optimum growth of the isolate occurred at NaCl concentrations of less than 50 mM. The G+C content of genomic DNA was around 67 mol%. The fatty acid profile of strain sk43HT when grown on acetate under aerobic conditions was characterized by the presence of C16 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) as the major components. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain was a member of the class Betaproteobacteria showing highest sequence similarity with Georgfuchsia toluolica G5G6T (94.7 %) and Denitratisoma oestradiolicum AcBE2-1T (94.3 %). Phylogenetic analyses were also performed using genes involved in sulfur oxidation. On the basis of its phylogenetic and phenotypic properties, strain sk43HT ( = DSM 22779T = NBRC 105852T) represents a novel species of a new genus, for which the name Sulfuritalea hydrogenivorans gen. nov., sp. nov. is proposed.
114 citations
TL;DR: While previous studies have suggested that most native Australian legumes nodulate primarily with species of the genus Bradyrhizobium, the results indicate significant associations with members of other root-nodule-forming bacterial genera, including Rhizobius, Ensifer, MesorhizOBium, Burkholderia, Phyllobacterium and Devosia.
Abstract: Symbiotic relationships between legumes and nitrogen-fixing soil micro-organisms are of ecological importance in plant communities worldwide. For example, nutrient-poor Australian soils are often dominated by shrubby legumes (e.g. species of Acacia). However, relatively few studies have quantified patterns of diversity, host-specificity and effectiveness of these ecologically important plant-microbe interactions. In this study, 16S rRNA gene sequence and PCR-RFLP analyses were used to examine bacterial strains isolated from the root nodules of two widespread south-eastern Australian legumes, Acacia salicina and Acacia stenophylla, across nearly 60 sites. The results showed that there was extensive genetic diversity in microbial populations, including a broad range of novel genomic species. While previous studies have suggested that most native Australian legumes nodulate primarily with species of the genus Bradyrhizobium, our results indicate significant associations with members of other root-nodule-forming bacterial genera, including Rhizobium, Ensifer, Mesorhizobium, Burkholderia, Phyllobacterium and Devosia. Genetic analyses also revealed a diverse suite of non-nodulating bacterial endophytes, only a subset of which have been previously recorded. Although the ecological roles of these endosymbionts are not well understood, they may play both direct and indirect roles in promoting plant growth, nodulation and disease suppression.
TL;DR: The results of DNA-DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain MH96(T) from the four most closely related Yersinia species with validly published names, including a Y. ruckeri isolate.
Abstract: A Gram-negative, rod-shaped, non-spore-forming bacterium (MH96T) was isolated from diseased larvae of the New Zealand grass grub, Costelytra zealandica (Coleoptera: Scarabaeidae). On the basis of 16S rRNA gene sequence similarity, strain MH96T is a member of the genus Yersinia, which is a member of the class Gammaproteobacteria. The most similar 16S rRNA gene sequence to that of MH96T is that of the type strain of Yersinia mollaretii (98.5 % similarity) followed by those of the type strains of Yersinia aldovae, Y. frederiksenii and Y. rohdei (all 98.4 % similarity). Multilocus sequence typing of five housekeeping genes (dnaJ, glnA, gyrB, groEL and recA) identified Yersinia ruckeri (81–92 % similarity) as the closest relative. The results of DNA–DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain MH96T from the four most closely related Yersinia species with validly published names, including a Y. ruckeri isolate. Strain MH96T therefore represents a novel species, for which the name Yersinia entomophaga sp. nov. is proposed, with the type strain MH96T ( = DSM 22339T = ATCC BAA-1678T).
TL;DR: Serological analysis, performed using the deformation test, did not reveal any reciprocal titres ≥320, indicating that strain TDA-040725-5(T) had minimal cross-reactivity to strains of recognized species of the genus Spiroplasma.
Abstract: A motile bacterium, designated strain TDA-040725-5T, was isolated from the haemolymph of a Chinese mitten crab, Eriocheir sinensis, with tremor disease. Based on 16S rRNA gene sequence analysis, the strain was phylogenetically distinct from other spiroplasmas but was closely related to Spiroplasma mirum ATCC 29335T. Cells of strain TDA-040725-5T were variable in length and shape, helical and motile, as determined by phase-contrast light microscopy. Examination by electron microscopy revealed wall-less cells delimited by a single membrane. The strain grew in M1D or R-2 liquid media at 20–40 °C, with optimum growth at 30 °C. Doubling time at the optimal temperature was 24 h. The strain catabolized glucose and hydrolysed arginine but did not hydrolyse urea. The DNA G+C content was 29.7±1 mol%. The genome size was ~1.4–1.6 Mbp. Serological analysis, performed using the deformation test, did not reveal any reciprocal titres ≥320, indicating that strain TDA-040725-5T had minimal cross-reactivity to strains of recognized species of the genus Spiroplasma. Based on this evidence, strain TDA-040725-5T ( = CCTCC M 207170T = DSM 21848T) represents a novel species of the genus Spiroplasma, for which the name Spiroplasma eriocheiris sp. nov. is proposed, belonging to the novel Spiroplasma serological group XLIII.
TL;DR: The results of DNA-DNA hybridizations, cellular fatty acid analysis and other differential phenotypic (physiological and biochemical) tests confirmed that strains A2, lac15, lac16 and lac31(T) represent a novel species of the genus Olsenella.
Abstract: Strain A2 is an anaerobic, variably Gram-stain-positive, non-spore-forming, small and irregularly rod-shaped bacterium from the ruminal fluid of a sheep that has been described informally as a representative of ‘Olsenella (basonym Atopobium) oviles’. Three phenotypically similar bacterial strains (lac15, lac16 and lac31T) were isolated in concert with Veillonella magna lac18T from the mucosal jejunum of a pig. A phylogenetic analysis based on 16S rRNA gene sequences revealed that strains A2, lac15, lac16 and lac31T formed a genetically coherent group (100 % interstrain sequence similarity) within the bigeneric Olsenella–Atopobium branch of the family Coriobacteriaceae, class Actinobacteria. This group was most closely related to the type strains of the two recognized Olsenella species, namely Olsenella uli (sequence similarity of 96.85 %) and Olsenella profusa (sequence similarity of 97.20 %). The sequence similarity to the type strain of Atopobium minutum, the type species of the genus Atopobium, was 92.33 %. Unlike those of O. uli and O. profusa, outgrown colonies of strains A2, lac15, lac16 and lac31T were opaque and greyish-white with an umbonate elevation on solid culture media. The four novel strains were characterized as being well-adapted and presumably indigenous to the gastrointestinal tract of homoeothermic vertebrates: they were mesophilic, microaerotolerant, neutrophilic and acidotolerant, bile-resistant, mucin-utilizing and markedly peptidolytic lactic acid bacteria. The results of DNA–DNA hybridizations, cellular fatty acid analysis and other differential phenotypic (physiological and biochemical) tests confirmed that strains A2, lac15, lac16 and lac31T represent a novel species of the genus Olsenella. On the basis of the genotypic and phenotypic results, we therefore describe Olsenella umbonata sp. nov., with lac31T ( = CCUG 58604T = DSM 22620T = JCM 16156T) as the type strain and A2 ( = CCUG 58212 = DSM 22619 = JCM 16157) as an additionally available reference strain. Also, based on our data, we propose emended descriptions of the genus Olsenella and the species Olsenella uli and Olsenella profusa.
TL;DR: Cl clustering of nodA and nifH gives additional support to the theory of monophyletic origin of the symbiotic genes in Bradyrhizobium and, in addition to the analysis of nodY/K and nodZ, indicates spread and maintenance of nod andnif genes through both vertical and horizontal transmission.
Abstract: Bacteria belonging to the genus Bradyrhizobium are capable of establishing symbiotic relationships with a broad range of plants belonging to the three subfamilies of the family Leguminosae ( = Fabaceae), with the formation of specialized structures on the roots called nodules, where fixation of atmospheric nitrogen takes place. Symbiosis is under the control of finely tuned expression of common and host-specific nodulation genes and also of genes related to the assembly and activity of the nitrogenase, which, in Bradyrhizobium strains investigated so far, are clustered in a symbiotic island. Information about the diversity of these genes is essential to improve our current poor understanding of their origin, spread and maintenance and, in this study, we provide information on 40 Bradyrhizobium strains, mostly of tropical origin. For the nodulation trait, common (nodA), Bradyrhizobium-specific (nodY/K) and host-specific (nodZ) nodulation genes were studied, whereas for fixation ability, the diversity of nifH was investigated. In general, clustering of strains in all nod and nifH trees was similar and the Bradyrhizobium group could be clearly separated from other rhizobial genera. However, the congruence of nod and nif genes with ribosomal and housekeeping genes was low. nodA and nodY/K were not detected in three strains by amplification or hybridization with probes using Bradyrhizobium japonicum and Bradyrhizobium elkanii type strains, indicating the high diversity of these genes or that strains other than photosynthetic Bradyrhizobium must have alternative mechanisms to initiate the process of nodulation. For a large group of strains, the high diversity of nod genes (with an emphasis on nodZ), the low relationship between nod genes and the host legume, and some evidence of horizontal gene transfer might indicate strategies to increase host range. On the other hand, in a group of five symbionts of Acacia mearnsii, the high congruence between nod and ribosomal/housekeeping genes, in addition to shorter nodY/K sequences and the absence of nodZ, highlights a co-evolution process. Additionally, in a group of B. japonicum strains that were symbionts of soybean, vertical transfer seemed to represent the main genetic event. In conclusion, clustering of nodA and nifH gives additional support to the theory of monophyletic origin of the symbiotic genes in Bradyrhizobium and, in addition to the analysis of nodY/K and nodZ, indicates spread and maintenance of nod and nif genes through both vertical and horizontal transmission, apparently with the dominance of one or other of these events in some groups of strains.
TL;DR: It is proposed that strain SMSP(T), isolated from an anaerobic, propionate-degrading enrichment culture that was originally obtained from granular sludge in a mesophilic upflowAnaerobic sludge blanket (UASB) reactor used to treat a beer brewery effluent, represents a novel species of the genus Methanoregula.
Abstract: A novel methane-producing archaeon, strain SMSPT, was isolated from an anaerobic, propionate-degrading enrichment culture that was originally obtained from granular sludge in a mesophilic upflow anaerobic sludge blanket (UASB) reactor used to treat a beer brewery effluent. Cells were non-motile, blunt-ended, straight rods, 1.0–2.6 μm long by 0.5 μm wide; cells were sometimes up to 7 μm long. Asymmetrical cell division was observed in rod-shaped cells. Coccoid cells (0.5–1.0 μm in diameter) were also observed in mid- to late-exponential phase cultures. Growth was observed between 10 and 40 °C (optimum, 30–33 °C) and pH 7.0 and 7.6 (optimum, pH 7.4). The G+C content of the genomic DNA was 56.2 mol%. The strain utilized formate and hydrogen for growth and methane production. Based on comparative sequence analyses of the 16S rRNA and mcrA (encoding the alpha subunit of methyl-coenzyme M reductase, a key enzyme in the methane-producing pathway) genes, strain SMSPT was affiliated with group E1/E2 within the order Methanomicrobiales. The closest relative based on both 16S rRNA and mcrA gene sequences was Methanoregula boonei 6A8T (96.3 % 16S rRNA gene sequence similarity, 85.4 % deduced McrA amino acid sequence similarity). The percentage of 16S rRNA gene sequence similarity indicates that strain SMSPT and Methanoregula boonei 6A8T represent different species within the same genus. This is supported by our findings of shared phenotypic properties, including cell morphology and growth temperature range, and phenotypic differences in substrate usage and pH range. Based on these genetic and phenotypic properties, we propose that strain SMSPT represents a novel species of the genus Methanoregula, for which we propose the name Methanoregula formicica sp. nov., with the type strain SMSPT (=NBRC 105244T =DSM 22288T).
TL;DR: Based on the properties of strain IC-180(T) determined in this polyphasic taxonomic study, this strain represents a novel species in a new genus in the order Acidimicrobiales, for which the name Aciditerrimonas ferrireducens gen. nov. is proposed.
Abstract: An iron-reducing, moderately thermophilic, acidophilic actinobacterium, strain IC-180T, isolated from a solfataric field in Hakone, Japan, was subjected to polyphasic taxonomic analysis. Strain IC-180T was a motile, short rod-shaped, Gram-positive bacterium that was able to grow at temperatures of 35–58 °C (optimally at 50 °C) and at pH 2.0–4.5 (optimally at pH 3.0). The strain grew aerobically and heterotrophically. It also grew anaerobically or autotrophically by dissimilatory reduction of ferric iron. No oxidation of ferrous iron was observed. Major cellular fatty acids detected were iso-C16 : 0, anteiso-C17 : 0 and iso-C18 : 0; the major menaquinone was MK-9(H8). Phosphatidyl-N-methylethanolamine and an unknown ninhydrin-positive phosphoglycolipid were detected. The total DNA G+C content was 74.1 mol%. 16S rRNA gene sequence comparisons revealed that strain IC-180T was a member of the order Acidimicrobiales and clustered coherently with uncultured actinobacteria from a geothermal site and a bioreactor operated under moderately thermophilic conditions. This cluster could be distinguished from the two other clusters comprising the families of this order, Acidimicrobiaceae and Iamiaceae, respectively. Based on the properties of strain IC-180T determined in this polyphasic taxonomic study, this strain represents a novel species in a new genus in the order Acidimicrobiales, for which the name Aciditerrimonas ferrireducens gen. nov., sp. nov. is proposed; the type strain is IC-180T ( = JCM 15389T = DSM 45281T).
TL;DR: In order to investigate which phytoplasmas constitute discrete, species-level taxa, several strains were analysed by comparing their 16S rRNA gene sequences and a set of five housekeeping genes and phylogenetic analysis showed that two discrete phylogenetic clusters could be clearly distinguished.
Abstract: In addition to the grapevine flavescence doree phytoplasmas, other members of taxonomic group 16SrV phytoplasmas infect grapevines, alders and species of the genera Clematis and Rubus in Europe. In order to investigate which phytoplasmas constitute discrete, species-level taxa, several strains were analysed by comparing their 16S rRNA gene sequences and a set of five housekeeping genes. Whereas 16S rRNA gene sequence similarity values were >97.5 %, the proposed threshold to distinguish two 'Candidatus Phytoplasma' taxa, phylogenetic analysis of the combined sequences of the tuf, rplV-rpsC, rplF-rplR, map and uvrB-degV genetic loci showed that two discrete phylogenetic clusters could be clearly distinguished. The first cluster grouped flavescence doree (FD) phytoplasmas, alder yellows (AldY) phytoplasmas, Clematis (CL) phytoplasmas and the Palatinate grapevine yellows (PGY) phytoplasmas. The second cluster comprised Rubus stunt (RS) phytoplasmas. In addition to the specificity of the insect vector, the Rubus stunt phytoplasma contained specific sequences in the 16S rRNA gene. Hence, the Rubus stunt phytoplasma 16S rRNA gene was sufficiently differentiated to represent a novel putative taxon: 'Candidatus Phytoplasma rubi'.
TL;DR: Phenotypic and physiological properties along with SDS-PAGE of whole-cell soluble proteins differentiated strain NRCPB10(T) from its closest phylogenetic neighbours and confirmed its position as distinct from recognized Rhizobium species.
Abstract: A novel bacterial strain, designated NRCPB10(T), was isolated from rhizosphere soil of chickpea (Cicer arietinum L.) in Pusa, New Delhi, India. The 16S rRNA gene sequence of strain NRCPB10(T) showed highest similarity (98.9 %) to that of Rhizobium radiobacter NCPPB 2437(T), followed by Rhizobium larrymoorei AF3-10(T) (97.7 %) and Rhizobium rubi IFO 13261(T) (97.4 %). Phylogenetic analysis of strain NRCPB10(T) based on the housekeeping genes recA and atpD confirmed its position as distinct from recognized Rhizobium species. Levels of DNA-DNA relatedness between strain NRCPB10(T) and R. radiobacter ICMP 5785(T), R. larrymoorei LMG 21410(T) and R. rubi ICMP 6428(T) were 51.0, 32.6 and 27.3 %, respectively. Cellular fatty acids of strain NRCPB10(T) were C(18 : 1)ω7c (58.9 %), C(16 : 0) (15.5 %), C(19 : 0) cyclo ω8c (11.5 %), iso-C(16 : 1) (5.8 %), C(16 : 0) 3-OH (4.5 %), C(16 : 1)ω7c (2.1 %) and C(18 : 0) (1.3 %). The G+C content of the genomic DNA of strain NRCPB10(T) was 59.0 mol%. Strain NRCPB10(T) did not nodulate chickpea plants or induce tumours in tobacco plants. Phenotypic and physiological properties along with SDS-PAGE of whole-cell soluble proteins differentiated strain NRCPB10(T) from its closest phylogenetic neighbours. On the basis of data from the present polyphasic taxonomic study, strain NRCPB10(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium pusense sp. nov. is proposed. The type strain is NRCPB10(T) ( = LMG 25623(T) = JCM 16209(T) = NCIMB 14639(T)).
TL;DR: Based on phenotypic, genetic and phylogenetic analysis, a novel species, Corynebacterium humireducens sp.
Abstract: A novel halotolerant, alkaliphilic, humic acid-reducing bacterium, designated MFC-5T, was isolated from a microbial fuel cell that was fed continuously with artificial wastewater (pH 10.0). Cells were Gram-positive-staining, facultatively anaerobic, non-fermentative, non-motile rods and had a G+C content of 59.0 mol%. Microbial growth was observed with 3 % 16S rRNA gene sequence divergence from its closest relatives. Based on phenotypic, genetic and phylogenetic analysis, a novel species, Corynebacterium humireducens sp. nov., is proposed. The type strain is MFC-5T ( = NBRC 106098T = CGMCC 2452T = DSM 45392T).
TL;DR: Three Gram-negative, motile, mesophilic, aerobic, rod-shaped bacterial strains isolate from Indonesian seawater exhibited high n-alkane-degrading activity, which indicated that the strains were important degraders of petroleum aliphatic hydrocarbons in tropical marine environments.
Abstract: Three Gram-negative, motile, mesophilic, aerobic, rod-shaped bacterial strains, designated 2O1T, 1O14 and 1O18, were isolated from Indonesian seawater after enrichment with crude oil and a continuous supply of supplemented seawater. The strains exhibited high n-alkane-degrading activity, which indicated that the strains were important degraders of petroleum aliphatic hydrocarbons in tropical marine environments. Phylogenetic analyses based on 16S rRNA gene sequences of members of the Gammaproteobacteria showed that the isolates formed a coherent and distinct cluster in a stable lineage containing Oceanobacter kriegii IFO 15467T (96.4–96.5 % 16S rRNA gene sequence similarity) and Thalassolituus oleivorans MIL-1T. DNA G +C content was 53.0–53.1 mol%. The major fatty acids were C16 : 0, C16 : 1
ω7 and C18 : 1
ω9 and the hydroxy fatty acids were C12 : 0 3-OH and C10 : 0 3-OH. The polar lipids were phosphatidylglycerol, a ninhydrin-positive phospholipid(s) and glycolipids. The major quinone was Q-9 (97–99 %), which distinguished the isolates from Oceanobacter kriegii NBRC 15467T (Q-8; 91 %). On the basis of phenotypic, genotypic and chemotaxonomic data, including DNA–DNA hybridization, the isolates represent a novel genus and species, for which the name Oleibacter marinus gen. nov., sp. nov. is proposed. The type strain of Oleibacter marinus is 2O1T (=NBRC 105760T =BTCC B-675T).
TL;DR: DNA-DNA hybridization together with chemotaxonomic data and biochemical characteristics allowed the differentiation of strain ICB 89(T) from its nearest phylogenetic neighbours and represents a novel species, for which the name Stenotrophomonas pavanii sp.
Abstract: A Gram-negative, rod-shaped, non-spore-forming and nitrogen-fixing bacterium, designated ICB 89T, was isolated from stems of a Brazilian sugar cane variety widely used in organic farming. 16S rRNA gene sequence analysis revealed that strain ICB 89T belonged to the genus Stenotrophomonas and was most closely related to Stenotrophomonas maltophilia LMG 958T, Stenotrophomonas rhizophila LMG 22075T, Stenotrophomonas nitritireducens L2T, [Pseudomonas] geniculata ATCC 19374T, [Pseudomonas] hibiscicola ATCC 19867T and [Pseudomonas] beteli ATCC 19861T. DNA–DNA hybridization together with chemotaxonomic data and biochemical characteristics allowed the differentiation of strain ICB 89T from its nearest phylogenetic neighbours. Therefore, strain ICB 89T represents a novel species, for which the name Stenotrophomonas pavanii sp. nov. is proposed. The type strain is ICB 89T ( = CBMAI 564T = LMG 25348T).
TL;DR: Results indicate that the isolates of the two groups belong to novel species within the genus Bifidobacterium, as proposed by phylogenetic and phenotypic analyses and analysis of 16S rRNA and partial hsp60 gene sequences.
Abstract: Our previous study, based primarily on PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing, focused on the isolation of four bifidobacterial groups from the digestive tract of three bumblebee species. In that study, we proposed that these isolated groups potentially represented novel species of the family Bifidobacteriaceae. One of the four, Bifidobacterium bombi, has been described recently. Strains representing two of the other groups have been classified as members of the genus Bifidobacterium on the basis of positive results for fructose-6-phosphate phosphoketolase activity and analysis of partial 16S rRNA and heat-shock protein 60 (hsp60) gene sequences. Analysis of 16S rRNA gene sequence similarities revealed that the isolates of the first group were affiliated to Bifidobacterium asteroides YIT 11866T, B. indicum JCM 1302T and B. coryneforme ATCC 25911T (96.2, 96.0 and 95.9 % sequence similarity, respectively), together with other bifidobacteria showing lower sequence similarity. Additional representatives of the second group were found to be affiliated to Bifidobacterium minimum YIT 4097T and B. coryneforme ATCC 25911T (96.0 and 96.3 % sequence similarity) and also to other bifidobacteria with lower sequence similarity. These results indicate that the isolates of the two groups belong to novel species within the genus Bifidobacterium. This observation was further substantiated by the results of partial sequencing of hsp60. On the basis of phylogenetic and phenotypic analyses and analysis of 16S rRNA and partial hsp60 gene sequences, we propose two novel species, Bifidobacterium actinocoloniiforme sp. nov. (type strain LISLUCIII-P2T = DSM 22766T = CCM 7728T) and Bifidobacterium bohemicum sp. nov. (type strain JEMLUCVIII-4T = DSM 22767T = CCM 7729T).
TL;DR: A study employing a polyphasic taxonomic approach was undertaken to clarify the position of 12 isolates recovered from sewage samples, revealing that this group of isolates represent a novel species of the genus Arcobacter.
Abstract: A study employing a polyphasic taxonomic approach was undertaken to clarify the position of 12 isolates recovered from sewage samples. These isolates were recognized as a potential novel species because a new and specific pattern was produced with the 16S rRNA-RFLP Arcobacter identification method. The sequences of the 16S rRNA gene not only supported the classification of these novel strains as members of the genus Arcobacter, but also showed that they formed a separate phylogenetic line. Strain SW28-11T, chosen as the representative of these strains, showed 16S rRNA gene sequence similarity of 95.6 % with the closest related species Arcobacter nitrofigilis. The phylogenetic position of the novel strains was further confirmed by analysis of the housekeeping genes hsp60, rpoB and, for the first time, gyrB. The latter proved to be an excellent additional gene for establishing the phylogeny of this genus. These data, together with phenotypic characterization, revealed that this group of isolates represent a novel species of the genus Arcobacter. The name Arcobacter defluvii sp. nov., is proposed, with the type strain SW28-11T ( = CECT 7697T = LMG 25694T).
TL;DR: Phylogenetic analysis of single gene alignments and a concatenated four-gene alignment demonstrated that the phy topathogenic species are taxonomically distinct from each other in spite of high 16S rRNA gene sequence similarities and provided a tool for the identification of unknown putative phytopathogenic Streptomyces strains at the species level.
Abstract: The identification and classification of species within the genus Streptomyces is difficult because there are presently 576 species with validly published names and this number increases every year. The value of multilocus sequence analysis applied to the systematics of Streptomyces species has been well demonstrated in several recently published papers. In this study the sequence fragments of four housekeeping genes, atpD, recA, rpoB and trpB, were determined for the type strains of 10 known phytopathogenic species of the genus Streptomyces, including Streptomyces scabiei, Streptomyces acidiscabies, Streptomyces europaeiscabiei, Streptomyces luridiscabiei, Streptomyces niveiscabiei, Streptomyces puniciscabiei, Streptomyces reticuliscabiei, Streptomyces stelliscabiei, Streptomyces turgidiscabies and Streptomyces ipomoeae, as well as six uncharacterized phytopathogenic Streptomyces isolates. The type strains of 52 other species, including 19 species observed to be phylogenetically closely related to these, based on 16S rRNA gene sequence analysis, were also included in the study. Phylogenetic analysis of single gene alignments and a concatenated four-gene alignment demonstrated that the phytopathogenic species are taxonomically distinct from each other in spite of high 16S rRNA gene sequence similarities and provided a tool for the identification of unknown putative phytopathogenic Streptomyces strains at the species level.
TL;DR: Five strains isolated from root nodules of Lablab purpureus and Arachis hypogaea grown in the Anhui and Sichuan provinces of China showed that the five strains clustered into a coherent group that differentiated them from all recognized species of the genus Bradyrhizobium.
Abstract: Five strains isolated from root nodules of Lablab purpureus and Arachis hypogaea grown in the Anhui and Sichuan provinces of China were classified as members of the genus Bradyrhizobium These strains had identical 16S rRNA gene sequences which shared 9948 %, 9948 % and 9922 % similarity with the most closely related strains of Bradyrhizobium jicamae PAC68T, Bradyrhizobium pachyrhizi PAC48T and Bradyrhizobium elkanii USDA 76T, respectively A study using a polyphasic approach, including 16S rRNA gene RFLP, IGS-RFLP, BOX-PCR, comparative sequence analysis of the 16S–23S rRNA intergenic spacer (IGS) and the recA, atpD and glnII genes, DNA–DNA hybridization and phenotypic tests, showed that the five strains clustered into a coherent group that differentiated them from all recognized species of the genus Bradyrhizobium Sequencing of nifH and nodC genes and cross-nodulation tests showed that the representative strains CCBAU 23086T, CCBAU 23160 and CCBAU 61434, isolated from different plants, had identical nifH and nodC gene sequences and were all able to nodulate Lablab purpureus, Arachis hypogaea and Vigna unguiculata Based upon these results, the name Bradyrhizobium lablabi sp nov is proposed for this novel species and strain CCBAU 23086T ( = LMG 25572T = HAMBI 3052T) is designated as the type strain The DNA G+C mol% is 6014 (T
m)
TL;DR: A novel chemolithoautotrophic, hyperthermophilic methanogen was isolated from a submarine hydrothermal system at the Kolbeinsey Ridge, north of Iceland and it is concluded that the novel strain represents a novel species of the genus Methanocaldococcus.
Abstract: A novel chemolithoautotrophic, hyperthermophilic methanogen was isolated from a submarine hydrothermal system at the Kolbeinsey Ridge, north of Iceland. Based on its 16S rRNA gene sequence, the strain belongs to the order Methanococcales within the genus Methanocaldococcus, with approximately 95 % sequence similarity to Methanocaldococcus jannaschii as its closest relative. Cells of the novel organism stained Gram-negative and appeared as regular to irregular cocci possessing more than 50 polar flagella. These cell appendages mediated not only motility but also adherence to abiotic surfaces and the formation of cell–cell contacts. The new isolate grew at 55–90 °C, with optimum growth at 80 °C. The optimum NaCl concentration for growth was 2.5 % (w/v), and the optimal pH was 6.5. The cells gained their energy exclusively by reduction of CO2 with H2. Selenate, tungstate and yeast extract stimulated growth significantly. The genome size was determined to be in the range 1.8–2.0 kb, and the G+C content of the genomic DNA was 30 mol%. Despite being physiologically nearly identical to the other members of the genus Methanocaldococcus, analysis of whole-cell proteins revealed significant differences. Based on the results from phylogenetic, morphological and protein analyses, we conclude that the novel strain represents a novel species of the genus Methanocaldococcus, for which the name Methanocaldococcus villosus sp. nov. is proposed (type strain KIN24-T80T = DSM 22612T = JCM 16315T).
TL;DR: An obligate piezophilic anaerobic hyperthermophilic archaeon, designated strain CH1(T), was isolated from a hydrothermal vent site named 'Ashadze', which is located on the Mid-Atlantic Ridge at a depth of 4100 m.
Abstract: An obligate piezophilic anaerobic hyperthermophilic archaeon, designated strain CH1(T), was isolated from a hydrothermal vent site named 'Ashadze', which is located on the Mid-Atlantic Ridge at a depth of 4100 m. Enrichment and isolation of the strain were carried out at 95 °C under a hydrostatic pressure of 42 MPa. Cells of strain CH1(T) were highly motile irregular cocci with a diameter of ~1-1.5 µm. Growth was recorded at 80-108 °C (optimum 98 °C) and at pressures of 20-120 MPa (optimum 52 MPa). No growth was observed under atmospheric pressures at 60-110 °C. Growth was observed at pH 6.0-9.5 (optimum 7.5-8.0) and in 2.5-5.5% (w/v) NaCl (optimum 3.5%). Strain CH1(T) was strictly anaerobic and grew on complex proteinaceous substrates, such as yeast extract, Peptone, and casein, as well as on sucrose, starch, chitin, pyruvate, acetate and glycerol without electron acceptors. The G+C content of the genomic DNA was 49.0±0.5 mol%. Analysis of 16S rRNA gene sequences revealed that strain CH1(T) belongs to the genus Pyrococcus. Based on its physiological properties and similarity levels between ribosomal proteins, strain CH1(T) represents a novel species, for which the name Pyrococcus yayanosii sp. nov. is proposed. The type strain is CH1(T) (=JCM 16557). This strain is also available by request from the Souchotheque de Bretagne (catalogue LMBE) culture collection (collection no. 3310).
TL;DR: Two Gram-negative, motile, aerobic bacterial strains, designated B2(T) and 1_C16_27(T), were respectively isolated from a seawater sample collected from the East China Sea and a semi-coke sample from north-eastern Estonia and their genetic, phenotypic and chemotaxonomic properties were studied.
Abstract: Two Gram-negative, motile, aerobic bacterial strains, designated B2T and 1_C16_27T, were respectively isolated from a seawater sample collected from the East China Sea and a semi-coke sample from north-eastern Estonia. Their genetic, phenotypic and chemotaxonomic properties were studied. The isolates were short rods with polar flagella and were positive for catalase and oxidase activities. Q-10 was the predominant respiratory ubiquinone. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and two unidentified glycolipids. The major fatty acids were nonadecanoic (C19 : 0 cyclo), octadecanoic (C18 : 0 and C18 : 0 3-OH), octadecenoic (C18 : 1) and hexadecanoic (C16 : 0) acids. The G+C content of the genomic DNA was 58.1–59.3 mol%. 16S rRNA gene sequence analysis revealed that the two isolates represent a distinct lineage within the family Hyphomicrobiaceae. The phylogenetically closest relatives were Cucumibacter (92.7–93.7 % 16S rRNA gene sequence similarity), Devosia (92.9–94.4 %) and Zhangella (91.7–92.1 %). Differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strains B2T and 1_C16_27T could be differentiated from each other and from members of the genera Cucumibacter, Devosia and Zhangella. Therefore, it is proposed that strains B2T and 1_C16_27T represent two novel species in a new genus, for which the names Pelagibacterium halotolerans gen. nov., sp. nov. (the type species; type strain B2T = CGMCC 1.7692T = JCM 15775T) and Pelagibacterium luteolum sp. nov. (type strain 1_C16_27T = CGMCC 1.10267T = JCM 16552T = CELMS EEUT 1C1627T) are proposed.
TL;DR: Genotypic and phenotypic data obtained in this study suggest that the C. villosus strains represent a novel Bradyrhizobium species most closely related to B. canariense BTA-1(T), and the type strain is CTAW11(T) (=LMG 25866(T)=CECT 7749(T)).
Abstract: Several strains isolated from Cytisus villosus nodules have been characterized based on their diverse genetic, phenotypic and symbiotic characteristics. According to 16S rRNA gene sequence analysis, the isolates formed a group that was closely related to Bradyrhizobium canariense BTA-1T with 99.4 % similarity. Analysis of three housekeeping genes, recA, atpD and glnII, suggested that the C. villosus strains represent a novel Bradyrhizobium species most closely related to B. canariense BTA-1T with similarities of 94.2, 96.7 and 94.5 %, respectively. All these differences were congruent with DNA–DNA hybridization analysis, which revealed 31 % relatedness between a representative strain (CTAW11T) isolated from C. villosus nodules and B. canariense BTA-1T. Phenotypic differences among the strains isolated from C. villosus and B. canariense were based on assimilation of carbon and nitrogen sources. The nodC and nifH genes of strain CTAW11T were phylogenetically related to those of strains belonging to bv. genistearum and divergent from those of bv. glycinearum and, accordingly, they do not nodulate soybean. Based on the genotypic and phenotypic data obtained in this study, our strains should be classified as representatives of a novel species for which the name Bradyrhizobium cytisi sp. nov. is proposed; the type strain is CTAW11T ( = LMG 25866T = CECT 7749T).