5S ribosomal RNA sequences were determined for thirteen actinomycetes mainly representatives with the rare group B type peptidoglycan. The primary and secondary structure of the resultant sequences were of the type characteristic of Gram-positive bacteria with DNA rich in guanine plus cytosine. The sequencing and associated chemotaxonomic data provide compelling grounds for classifying actinomycetes with a group B type peptidoglycan in a single family. The family Microbacteriaceae fam. nov. is proposed to accommodate actinomycetes classified in the genera Agromyces, Aureobacterium, Clavibacter, Curtobacterium and Microbacterium.

Three novel bacterial strains, designated Vu-144 T , Vu-7 and Vu-35, were isolated on minimal medium from rhizosphere soil of field-grown cowpea and subjected to a taxonomic study using a polyphasic approach. Cells of the strains were Gram-stain-negative, non-motile, non-sporeforming, coccoid rods, and formed non-pigmented colonies. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Vu-144 T was affiliated with an uncultivated lineage of the phylum Bacteroidetes. Its closest phylogenetic neighbour was the recently described species Niastella populi, a member of the family Chitinophagaceae, with just 90.7 % sequence similarity to the type strain. The only isoprenoid quinone detected was menaquinone 7 (MK-7). The fatty acid profiles showed large amounts of iso-C 15 : 0 , iso-C 17 : 0 3-OH and iso-C 15 : 1 G and minor amounts of summed feature 3 (C 16 : 1 v7c and/or iso-C 15 : 0 2-OH), C 16 : 0 and other fatty acids, allowing the differentiation of the strains from other genera. The G+C content of the genomic DNA of the three strains ranged from 43.1 to 44.3 mol%. In addition to phosphatidylethanolamine, the major polar lipids were three unidentified aminophospholipids (APL1-APL3), two unidentified phospholipids (PL1, PL2) and three unidentified lipids (UL1-UL3). Biochemical test patterns also differed from those of Niastella populi and members of other genera. All three isolates showed plant-growth-promoting properties, e.g. the ability to produce indole-3-acetic acid and NH 3 and to solubilize phosphate, utilized 1-aminocyclopropane 1-carboxylate (ACC) as a sole source of nitrogen and possessed the ACC deaminase enzyme. The novel isolates readily colonized roots and stimulated growth of tomato and cowpea under glasshouse conditions. Inoculated plants showed a 45-60 % increase in dry matter weight with respect to uninoculated controls. On the basis of the evidence from our polyphasic study, isolate Vu-144 T represents a novel genus and species in the family Chitinophagaceae, for which the name Arachidicoccus rhizosphaerae gen. nov., sp. nov. is proposed. The type strain of Arachidicoccus rhizosphaerae is Vu-144 T (5KCTC 22378 T 5NCIMB 14473 T). Abbreviations: ACC, 1-aminocyclopropane 1-carboxylate; IAA, indole-3acetic acid. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains Vu-144 T , Vu-35 and Vu-7 are EU672808, EU672809 and EU672810, respectively. Two supplementary tables and five supplementary figures are available with the online Supplementary Material.

A methylotrophic nitrogen-fixing bacterial strain, Ah-143 T , isolated from the rhizosphere soil of field-grown groundnut was analysed by a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis combined with rpoB gene sequence analysis allocated strain Ah-143 T to the family Enterobacteriaceae, with Enterobacter radicincitans and Enterobacter cowanii as the closest relatives. The strain is Gram-stain-negative, non-spore-forming, aerobic and motile, having straight rod-shaped cells with a DNA G+C content of approximately 53.2 mol%. The strain utilizes methanol as a carbon source and the mxaF gene was closely related to the mxaF gene of members of the genus Methylobacterium. The fatty acid profile consisted of C 16 : 0 , C 17 : 0 cyclo, C 18 : 1 v7c, summed feature 2 (iso-C 16 : 1 I and/or C 14 : 0 3-OH) and summed feature 3 (iso-C 15 : 0 2-OH and/or C 16 : 1 v7c) as the major components. DNA-DNA relatedness of strain Ah-143 T with its close relatives was less than 20 %. On the basis of the phylogenetic analyses, DNA-DNA hybridization data, and unique physiological and biochemical characteristics, it is proposed that the strain represents a novel species of the genus Enterobacter and should be named Enterobacter arachidis sp. nov. The type strain is Ah-143 T (5NCIMB 14469 T 5KCTC 22375 T ).The genus Enterobacter is clearly separated from other groups, forming a distinct branch, and at the time of writing included 22 species with validly published names (http://www.bacterio.cict.fr/e/enterobacter.html), Enterobacter cloacae being the type species (Hormaeche & Edwards, 1960). Members of the genus Enterobacter are detected in various environments, such as infant formula (Stephan et al., 2007(Stephan et al., , 2008, clinical specimens (Brenner et al., 1986;Hoffmann et al., 2005) and in association with plants (Egamberdieva et al., 2008; Kämpfer et al., 2005). Several species of the genus Enterobacter are known to interact and exert beneficial effects on plant growth. The plant-growthpromoting effects of beneficial bacteria may occur through direct or indirect mechanisms that include production of phytohormones or enzymes that promote plant growth, increased nutrient uptake, and prevention of deleterious phytopathogens (Glick et al., 1999;Whipps, 2001). The complex mixture of carbohydrates, amino acids, organic acids and other nutrients released from seeds and roots are thought to support the growth of beneficial bacteria such as E. cloacae in the spermosphere and rhizosphere. E. cloacae colonizes the spermospheres and rhizospheres of a number Abbreviation: ACCD, 1-aminocyclopropane-1-carboxylate deaminase.The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA, rpoB, nifH and mxaF gene sequences of strain Ah-143 T are EU672801, FJ768683, FJ460712 and EU912491, respectively.Phase-contrast and scanning electron micrographs of cells of strain Ah-143 T , phylogenetic trees based on rpoB and nifH gene sequences, and cellular fatty acid compositions of strain Ah-143 T and related species of the genus...

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Microbacterium strain AI-S262T was isolated from the rhizoplane of neem seedlings in the Botanical garden of Tamilnadu Agricultural University, Coimbatore, India, and subjected to phenotypic, chemotaxonomic and genetic characterization. Cells of this strain were Gram-stainpositive, motile, non-spore-forming, short rods and formed light-yellow-pigmented colonies on nutrient agar. Strain AI-S262 T contained MK-12 and MK-13 as the main respiratory quinones, anteiso-C 15 : 0 , anteiso-C 17 : 0 and iso-C 16 : 0 as the predominant fatty acids, peptidoglycan-type B2b with glycolyl residues, and had a DNA G+C content of 69.5 mol%. A phylogenetic analysis based on 16S rRNA gene sequences showed 98.0-98.6 % pair-wise similarity with respect to close relatives in the genus Microbacterium. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 39%) between strain AI-S262 T and its closest relatives.Data from DNA-DNA hybridization and phenotypic analyses supported the conclusion that strain AI-S262 T represents a novel species in the genus Microbacterium, for which the name