title: Arachidicoccus rhizosphaerae gen. nov., sp. nov., a plant-growth-promoting bacterium in the family Chitinophagaceae isolated from rhizosphere soil.
abstract: 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-spore-forming, 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-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G and minor amounts of summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 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 NH3 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) ( = KCTC 22378(T) = NCIMB 14473(T)).
authors.affiliation: Temasek Lifesciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.|Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India.
authors.forename: Munusamy
authors.initials: M
authors.lastname: Madhaiyan
authors.affiliation: Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India.
authors.forename: Selvaraj
authors.initials: S
authors.lastname: Poonguzhali
authors.affiliation: Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India.
authors.forename: Murugaiyan
authors.initials: M
authors.lastname: Senthilkumar
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
authors.forename: Dhandapani
authors.initials: D
authors.lastname: Pragatheswari
authors.affiliation: Korean Collection for Type Cultures, Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology, 111 Gwahangno, Yusong-gu, Daejeon 305-806, Republic of Korea.
authors.forename: Jung-Sook
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Korean Collection for Type Cultures, Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology, 111 Gwahangno, Yusong-gu, Daejeon 305-806, Republic of Korea.
authors.forename: Keun-Chul
authors.initials: KC
authors.lastname: Lee
mesh_terms: D010367:Arachis / Q000382:microbiology; D015373:Bacterial Typing Techniques; D041963:Bacteroidetes / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D001482:Base Composition; D004269:DNA, Bacterial / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology; D005227:Fatty Acids / Q000737:chemistry; D007194:India; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D024482:Vitamin K 2 / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D024482:Vitamin K 2; C062629:menaquinone 7