Halomonas citrativorans sp. nov., Halomonas casei sp. nov. and Halomonas colorata sp. nov., isolated from French cheese rinds.

Eight Gram-stain-negative bacterial strains were isolated from cheese rinds sampled in France. On the basis of 16S rRNA gene sequence analysis, all isolates were assigned to the genus Halomonas. Phylogenetic investigations, including 16S rRNA gene studies, multilocus sequence analysis, reconstruction of a pan-genome phylogenetic tree with the concatenated core-genome content and average nucleotide identity (ANI) calculations, revealed that they constituted three novel and well-supported clusters. The closest relative species, determined using the whole-genome sequences of the strains, were Halomonas zhanjiangensis for two groups of cheese strains, sharing 82.4 and 93.1 % ANI, and another cluster sharing 92.2 % ANI with the Halomonas profundi type strain. The strains isolated herein differed from the previously described species by ANI values <95 % and several biochemical, enzymatic and colony characteristics. The results of phenotypic, phylogenetic and chemotaxonomic analyses indicated that the isolates belonged to three novel Halomonas species, for which the names Halomonas citrativorans sp. nov., Halomonas casei sp. nov. and Halomonas colorata sp. nov. are proposed, with isolates FME63T (=DSM 113315T=CIRM-BIA2430T=CIP 111880T=LMG 32013T), FME64T (=DSM 113316T=CIRM-BIA2431T=CIP 111877T=LMG 32015T) and FME66T (=DSM 113318T=CIRM-BIA2433T=CIP 111876T=LMG 32014T) as type strains, respectively.

Genomics of the "tumorigenes" clade of the family Rhizobiaceae and description of Rhizobium rhododendri sp. nov.

Tumorigenic members of the family Rhizobiaceae, known as agrobacteria, are responsible for crown and cane gall diseases of various crops worldwide. Tumorigenic agrobacteria are commonly found in the genera Agrobacterium, Allorhizobium, and Rhizobium. In this study, we analyzed a distinct "tumorigenes" clade of the genus Rhizobium, which includes the tumorigenic species Rhizobium tumorigenes, as well as strains causing crown gall disease on rhododendron. Here, high-quality, closed genomes of representatives of the "tumorigenes" clade were generated, followed by comparative genomic and phylogenomic analyses. Additionally, the phenotypic characteristics of representatives of the "tumorigenes" clade were analyzed. Our results showed that the tumorigenic strains isolated from rhododendron represent a novel species of the genus Rhizobium for which the name Rhizobium rhododendri sp. nov. is proposed. This species also includes additional strains originating from blueberry and Himalayan blackberry in the United States, whose genome sequences were retrieved from GenBank. Both R. tumorigenes and R. rhododendri contain multipartite genomes, including a chromosome, putative chromids, and megaplasmids. Synteny and phylogenetic analyses indicated that a large putative chromid of R. rhododendri resulted from the cointegration of an ancestral megaplasmid and two putative chromids, following its divergence from R. tumorigenes. Moreover, gene clusters specific for both species of the "tumorigenes" clade were identified, and their biological functions and roles in the ecological diversification of R. rhododendri and R. tumorigenes were predicted and discussed.

Two New Rhizobiales Species Isolated from Root Nodules of Common Sainfoin (Onobrychis viciifolia) Show Different Plant Colonization Strategies.

Root nodules of legume plants are primarily inhabited by rhizobial nitrogen-fixing bacteria. Here, we propose two new Rhizobiales species isolated from root nodules of common sainfoin (Onobrychis viciifolia), as shown by core-gene phylogeny, overall genome relatedness indices, and pan-genome analysis. Mesorhizobium onobrychidis sp. nov. actively induces nodules and achieves atmospheric nitrogen and carbon dioxide fixation. This species appears to be depleted in motility genes and is enriched in genes for direct effects on plant growth performance. Its genome reveals functional and plant growth-promoting signatures, like a large unique chromosomal genomic island with high density of symbiotic genetic traits. Onobrychidicola muellerharveyae gen. nov. sp. nov. is described as a type species of the new genus Onobrychidicola in Rhizobiaceae. This species comprises unique genetic features and plant growth-promoting traits (PGPTs), which strongly indicate its function in biotic stress reduction and motility. We applied a newly developed bioinformatics approach for in silico prediction of PGPTs (PGPT-Pred), which supports the different lifestyles of the two new species and the plant growth-promoting performance of M. onobrychidis in the greenhouse trial. IMPORTANCE The intensive use of chemical fertilizers has a variety of negative effects on the environment. Increased utilization of biological nitrogen fixation (BNF) is one way to mitigate those negative impacts. In order to optimize BNF, suitable candidates for different legume species are required. Despite intensive search for new rhizobial bacteria associated with legumes, no new rhizobia have recently been identified from sainfoin (Onobrychis viciifolia). Here, we report on the discovery of two new rhizobial species associated with sainfoin, which are of high importance for the host and may help to increase sustainability in agricultural practices. We employed the combination of in silico prediction and in planta experiments, which is an effective way to detect promising plant growth-promoting bacteria.

Phylogenomics reveals the basis of adaptation of Pseudorhizobium species to extreme environments and supports a taxonomic revision of the genus.

The family Rhizobiaceae includes many genera of soil bacteria, often isolated for their association with plants. Herein, we investigate the genomic diversity of a group of Rhizobium species and unclassified strains isolated from atypical environments, including seawater, rock matrix or polluted soil. Based on whole-genome similarity and core genome phylogeny, we show that this group corresponds to the genus Pseudorhizobium. We thus reclassify Rhizobium halotolerans, R. marinum, R. flavum and R. endolithicum as P. halotolerans sp. nov., P. marinum comb. nov., P. flavum comb. nov. and P. endolithicum comb. nov., respectively, and show that P. pelagicum is a synonym of P. marinum. We also delineate a new chemolithoautotroph species, P. banfieldiae sp. nov., whose type strain is NT-26T (=DSM 106348T=CFBP 8663T). This genome-based classification was supported by a chemotaxonomic comparison, with increasing taxonomic resolution provided by fatty acid, protein and metabolic profiles. In addition, we used a phylogenetic approach to infer scenarios of duplication, horizontal transfer and loss for all genes in the Pseudorhizobium pangenome. We thus identify the key functions associated with the diversification of each species and higher clades, shedding light on the mechanisms of adaptation to their respective ecological niches. Respiratory proteins acquired at the origin of Pseudorhizobium were combined with clade-specific genes to enable different strategies for detoxification and nutrition in harsh, nutrient-poor environments.

Hydrobacter penzbergensis gen. nov., sp. nov., isolated from purified water.

A Gram-negative, oxidase- and catalase-positive bacterium, designated strain EM 4(T), which varied in shape from rod-shaped to curved or helical with frequently observed bulb-shaped protuberances, was isolated from purified water. 16S rRNA gene sequence analysis indicated that the novel strain belongs to the family Chitinophagaceae within the phylum Bacteroidetes; the closest relative among bacterial species with validly published names was determined to be Sediminibacterium salmoneum NBRC 103935(T), with 93.4 % sequence identity. The main fatty acids of strain EM 4(T) were iso-C15 : 0, iso-C15 : 1 and iso-C17 : 0 3-OH. The polar lipid profile consisted of phosphatidylethanolamine, aminolipids, aminophospholipids and unknown lipids; the quinone system consisted of menaquinone MK-7. 16S rRNA gene sequence analysis and the polar lipid and fatty acid profiles suggest that the strain represents a novel genus and species, for which the name Hydrobacter penzbergensis gen. nov., sp. nov. is proposed. The type strain of Hydrobacter penzbergensis is strain EM 4(T) ( = DSM 25353(T) = CCUG 62278(T)).

Dissection of the genus Methylibium: reclassification of Methylibium fulvum as Rhizobacter fulvus comb. nov., Methylibium aquaticum as Piscinibacter aquaticus gen. nov., comb. nov. and Methylibium subsaxonicum as Rivibacter subsaxonicus gen. nov., comb. nov. and emended descriptions of the genera Rhizobacter and Methylibium.

16S rRNA gene sequenced-based phylogeny indicates that Rhizobacter dauci ATCC 43778(T) branches within the radiation of Methylibium type strains. A comparative chemotaxonomic study including fatty acid methyl esters, polar lipids and polyamines reveals significant differences that, in combination with the topology of phylogenetic trees, support a dissection of the genus Methylibium. The proposals of this study include the transfer of Methylibium fulvum to the genus Rhizobacter as Rhizobacter fulvus comb. nov. (type strain Gsoil 322(T) =KCTC 12591(T) =DSM 19916(T)) and the reclassification of Methylibium aquaticum as Piscinibacter aquaticus gen. nov., comb. nov. (the type strain of Piscinibacter aquaticus is IMCC1728(T) =KCCM 42364(T) =NBRC 102349(T) =DSM 19915(T)) and of Methylibium subsaxonicum as Rivibacter subsaxonicus gen. nov., comb. nov. (the type strain of Rivibacter subsaxonicus is BF49(T) =DSM 19570(T) =CIP 109700(T)). As a consequence of these reclassifications, emended descriptions of the genera Methylibium and Rhizobacter are provided.

Flavobacterium rivuli sp. nov., Flavobacterium subsaxonicum sp. nov., Flavobacterium swingsii sp. nov. and Flavobacterium reichenbachii sp. nov., isolated from a hard water rivulet.

Strains WB 3.3-2(T), WB 3.2-61(T), WB 4.1-42(T) and WB 2.3-68(T) were isolated from the Westerhöfer Bach hard water rivulet, North Germany. The strains were Gram-staining-negative and catalase-, aminopeptidase- and oxidase-positive. The novel strains lacked flagella and only strain WB3.2-61(T) showed gliding motility. Isolates WB 3.2-61(T), WB 4.1-42(T) and WB 2.3-68(T) produced flexirubin pigments. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strains showed <98.2 % similarity to the type strains of all recognized species of the genus Flavobacterium. Strains WB 3.3-2(T) and WB 4.1-42(T) shared 96.3 % sequence similarity and were only distantly related to the type strains of all of the members of the genus Flavobacterium. Strain WB 3.2-61(T) branched adjacent to Flavobacterium limicola DSM 15094(T) (98.0 %), while strain WB 2.3-68(T) was a neighbour of Flavobacterium psychrophilum DSM 3660(T) (97.1 %). On R2A medium, iso-C(15 : 0) was the common major fatty acid; fatty acids C(15 : 0), C(16 : 0), iso-C(15 : 0) 3-OH, iso-C(17 : 1)omega9c, iso-C(17 : 0) 3-OH and summed feature 3 (comprising C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH) occurred in all strains though sometimes in low amounts. Metabolic properties revealed clear differences between the four isolates as well as between the isolates and their nearest phylogenetic neighbours. The lack of close relatedness was confirmed by Riboprinter and MALDI-TOF analyses of cell extracts. On the basis of a high number of phenotypic differentiating properties and phylogenetic uniqueness, four novel Flavobacterium species are proposed with the following names: Flavobacterium rivuli (type strain WB 3.3-2(T)=DSM 21788(T)=CIP 109865(T)), Flavobacterium subsaxonicum (type strain WB 4.1-42(T)=DSM 21790(T)=CIP 109867(T)), Flavobacterium swingsii (type strain WB 2.3-68(T)=DSM 21789(T)=CIP 109868(T)) and Flavobacterium reichenbachii (type strain WB 3.2-61(T)=DSM 21791(T)=CIP 109866(T)).

Biostraticola tofi gen. nov., spec. nov., a novel member of the family Enterobacteriaceae.

Bacterial strain BF36T, isolated from the biofilm of a tufa deposit in a hard water rivulet, was characterized by a polyphasic taxonomic approach. Cells of these organisms were Gram-negative, motile, nonpigmented, rod-shaped, non-endospore-forming, and facultatively anaerobic. Cells, organized in loose consortia, were coated by a massive slime layer. Phylogenetic analyses using 16S rRNA gene sequences showed that strain BF36T was a member of the family Enterobacteriaceae, class Gammaproteobacteria, displaying a moderate degree of relationship (96.5% sequence similarity) to Sodalis glossinidius and "Sodalis pallipedes," intracellular symbionts of the tsetse fly Glossinis morsitans morsitans. Dendrograms of relationship generated by different algorithms consistently grouped isolate BF36T with Sodalis glossinidius, Pragia fontium, Budvicia aquatica, Serratia rubideae, and Brenneria spp (94.7-95.8% similarity) which also share many common metabolic properties. Differences between strain BF36T and Sodalis glossinidius DSM 13495T are seen in motility and in the pattern of substrates utilized. Membership to the family was also confirmed by a fatty acid profile consisting of major amounts of C16:0)and C16:1omega7, by the presence of isoprenoids of the ubiquinone Q8 and menaquinone MK8 types and a DNA G + C content of 54.2 mol%. The decision to classify strain BF36T into a new genus Biostraticola gen. nov. is based on its distant phylogenetic position as compared to any other representative of the family and the significant phenotypic differences to its nearest phylogenetic neighbor, Sodalis glossinidius. BF36T represents the type species, for which the name Biostraticola tofi sp. nov. is proposed. The type strain is BF36T (DSM 19580T; CIP109699T).

Methylibium subsaxonicum spec. nov., a betaproteobacterium Isolated from a hardwater rivulet.

A single strain, designated BF49(T), was isolated from a biofilm of a tufa deposit from the Westerhöfer rivulet, Lower Saxony, Germany. The G+C content of the genomic DNA of strain BF49(T) was 69 mol% and the predominant ubiquinone was Q-8. Major fatty acids were C(16:1)omega7c/15 iso 2OH and C(16:0). Comparative 16S rRNA gene sequence analysis indicated that the isolate was placed within the genus Methylibium, class Betaproteobacteria, distantly related to the type strain Methylibium petroleiphilum LMG 22953(T) (97.4% similarity), Methylibium fulvum Gsoil 322(T )(96%), and Methylibium aquaticum IMCC1728(T )(95.7%). On the basis of phylogenetic and phenotypic distinctness we propose a novel species, Methylibium subsaxonicum sp. nov., with strain BF49(T) (DSM 19570(T), CIP 109700(T)) as the type strain.

Erysipelothrix inopinata sp. nov., isolated in the course of sterile filtration of vegetable peptone broth, and description of Erysipelotrichaceae fam. nov.

Based on 16S rRNA gene sequence comparison, an isolate that was detected in sterile-filtered vegetable broth was classified as a novel member of the Erysipelothrix line of descent of the Firmicutes. Strain MF-EP02T resembles members of the two species of Erysipelothrix with validly published names, Erysipelothrix rhusiopathiae and Erysipelothrix tonsillarum, in morphology, fatty acid composition, lack of menaquinones in aerobically and anaerobically grown cultures, DNA G+C content and peptidoglycan amino acid composition. Distinct differences in physiological characteristics, however, support the allocation of this isolate to a novel species of the genus Erysipelothrix, for which the name Erysipelothrix inopinata sp. nov. (type strain, MF-EP02T=DSM 15511T=CIP 107935T) is proposed. Members of the Erysipelothrix line of descent are included in the family Erysipelotrichaceae fam. nov.

Exiguobacterium undae sp. nov. and Exiguobacterium antarcticum sp. nov.

Four orange-pigmented strains from pond water (L1-L4) have been subjected to polyphasic taxonomic analyses. On the basis of ribotype analysis and Fourier-transform infrared spectroscopy, these strains form a genomically highly related group. 16S rDNA sequence analysis revealed 98.8% similarity between the 16S rDNA sequences of strains L2T and H2T, isolated previously from a microbial mat from Lake Fryxell, Antarctica. DNA-DNA reassociation values indicated the presence of two genomic clusters. While the DNA of strains L2T and L3 showed 100% DNA relatedness, strains L2T and H2T shared only 51% DNA relatedness. These two clusters differed in some phenotypic properties, e.g. utilization of melibiose, D-mannitol, adenosine 5'-monophosphate and uridine 5'-monophosphate, and in their fatty acid compositions. Based on the composition of isoprenoid quinones, peptidoglycan, polar lipids and fatty acids, these organisms are members of the genus Exiguobacterium. This is supported by 16S rDNA analyses, which revealed 97-98% similarity to Exiguobacterium acetylicum DSM 20416T and 93.2-93.8% similarity to Exiguobacterium aurantiacum DSM 6208T. E. acetylicum DSM 20416T, the closest phylogenetic neighbour, shows only 39% DNA similarity to strain L2T and 40% DNA similarity to strain H2T. Based on genomic distinctiveness and the clear differences in chemotaxonomy and physiology, two novel species are proposed, Exiguobacterium undae sp. nov. and Exiguobacterium antarcticum sp. nov.