Burkholderia humisilvae sp. nov., Burkholderia solisilvae sp. nov. and Burkholderia rhizosphaerae sp. nov., isolated from forest soil and rhizosphere soil

Strains Y-12T and Y-47T were isolated from mountain forest soil and strain WR43T was isolated from rhizosphere soil, at Daejeon, Korea. The three strains grew at 10–55 °C (optimal growth at 28–30 °C), at pH 3.0–8.0 (optimal growth at pH 6.0) and in the presence of 0–4.0  % (w/v) NaCl, growing optimally in the absence of added NaCl. On the basis of 16S rRNA gene sequence analysis, the three strains were found to belong to the genus Burkholderia, showing the closest phylogenetic similarity to Burkholderia diazotrophica JPY461T (97.2–97.7  %); the similarity between the three sequences ranged from 98.3 to 98.7  %. Additionally, the three strains formed a distinct group in phylogenetic trees based on the housekeeping genes recA and gyrB. The predominant ubiquinone was Q-8, the major fatty acids were C16 : 0 and C17 : 0 cyclo and the DNA G+C content of the novel isolates was 61.6–64.4 mol%. DNA–DNA relatedness among the three strains and the type strains of the closest species of the genus Burkholderia was less than 50  %. On the basis of 16S rRNA, recA and gyrB gene sequence similarities, chemotaxonomic and phenotypic data, the three strains represent three novel species within the genus Burkholderia, for which the names Burkholderia humisilvae sp. nov. (type strain Y-12T = KACC 17601T = NBRC 109933T = NCAIM B 02543T), Burkholderia solisilvae sp. nov. (type strain Y-47T = KACC 17602T = NBRC 109934T = NCAIM B 02539T) and Burkholderia rhizosphaerae sp. nov. (type strain WR43T = KACC 17603T = NBRC 109935T = NCAIM B 02541T) are proposed.