Burkholderia sabiae sp. nov., isolated from root nodules of Mimosa caesalpiniifolia Wen-Ming Chen, 1 Sergio M. de Faria, 2 Jui-Hsing Chou, 3 Euan K. James, 4 Geoffrey N. Elliott, 4 Janet I. Sprent, 4 Cyril Bontemps, 5 J. Peter W. Young 5 and Peter Vandamme 6 Correspondence Wen-Ming Chen p62365@ms28.hinet.net 1 Laboratory of Microbiology, Department of Seafood Science, National Kaohsiung Marine University, 142 Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan 2 EMBRAPA-Agrobiologia, km 47, Seropedica, 23851-970 Rio de Janeiro, Brazil 3 Department of Soil Environmental Science, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan 4 College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK 5 Department of Biology, University of York, PO Box 373, York YO10 5YW, UK 6 Laboratorium voor Microbiologie, Universiteit Gent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium Two rhizobial strains, Br3407 T and Br3405, were isolated from nitrogen-fixing nodules on the roots of Mimosa caesalpiniifolia, a legume tree native to Brazil. On the basis of 16S rRNA gene sequence similarities, both strains were shown previously to belong to the genus Burkholderia. A polyphasic approach, including DNA–DNA hybridizations, pulsed-field gel electrophoresis of whole-genome DNA profiles, whole-cell protein analyses, fatty acid methyl ester analysis and extensive biochemical characterization, was used to clarify the taxonomic position of these strains further; the strains are here classified within a novel species, for which the name Burkholderia sabiae sp. nov. is proposed. The type strain is strain Br3407 T (5LMG 24235 T 5BCRC 17587 T ). Plants in the legume genus Mimosa (in the subfamily Mimosoideae) are largely nodulated by members of the Betaproteobacteria, such as Cupriavidus taiwanensis and Burkholderia strains (Chen et al., 2001, 2003a, b, 2005a, b; Vandamme & Coenye, 2004; Verma et al., 2004; Barrett & Parker, 2005, 2006; Elliott et al., 2007). Symbiont diversity within the genus Cupriavidus appears to be quite low based upon 16S rRNA gene sequences, and only one nodulating species of Cupriavidus, C. taiwanensis (Chen et al., 2001), has been described so far. However, in contrast to Cupriavidus, the diversity of Burkholderia symbionts associated with legumes is very high (Chen et al., 2005a, b; Barrett & Parker, 2005, 2006), and two novel Mimosa- nodulating species, Burkholderia mimosarum (Chen et al., 2006) and Burkholderia nodosa (Chen et al., 2007), have recently been added to the genus. Together with Burkholderia phymatum and Burkholderia tuberum (Moulin et al., 2001; Vandamme et al., 2002), this brings the number of legume-nodulating Burkholderia species to four, but 16S rRNA gene sequences in the literature and databases suggest that several other species await descrip- tion. For example, amongst the group of South American Mimosa symbionts described by Chen et al. (2005a) that gave rise to both B. mimosarum and B. nodosa (Chen et al., 2006, 2007), there are other clades containing strains that cluster very closely together. In this paper, we describe a novel Mimosa-nodulating species based upon two strains, Br3405 and Br3407 T , both isolated from Mimosa caesalpi- niifolia, a legume tree native to Brazil. Both Br3405 and Br3407 T were grown on yeast extract- mannitol agar plates (Vincent, 1970) and incubated at 28 u C unless otherwise indicated. Burkholderia reference strains have been described previously (Achouak et al., 1999; Vandamme et al., 2002; Goris et al., 2002; Yang et al., 2006). The 16S rRNA gene sequences of strains Br3407 T and Br3405 have been reported by Chen et al. (2005a). 16S rRNA gene sequences of related taxa were obtained from the Ribosomal Database Project and GenBank databases. Abbreviation: PFGE, pulsed-field gel electrophoresis. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains Br3407 T and Br3405 are respectively AY773186 and AY773185. An extended neighbour-joining tree, detailed DNA–DNA hybridization results and fatty acid compositions of strain Br3407 T and related strains are available as supplementary material with the online version of this paper. International Journal of Systematic and Evolutionary Microbiology (2008), 58, 2174–2179 DOI 10.1099/ijs.0.65816-0 2174 65816 G 2008 IUMS Printed in Great Britain