Herbaspirillum rhizosphaerae sp. nov., isolated from rhizosphere soil of Allium victorialis var. platyphyllum

Abstract

Two Gram-negative, milky-white-pigmented, motile, slightly curved rod-shaped bacterial isolates, UMS-37T and UMS-40, were isolated from rhizosphere soil of wild edible greens cultivated on Ulleung island, Korea, and their taxonomic positions were investigated by a polyphasic approach. They grew optimally at 25-30 °C and contained O-8 as the predominant ubiquinone. The major cellular fatty acids (>10% of total fatty acids) were C16:0, cyclo C17:0 and Cir16:1ω7c and/or iso-C15:0 2-OH. The DNA G + C contents of the two isolates were 59.8 and 60.0 mol%. Isolates UMS-37T and UMS-40 exhibited no difference in their 16S rRNA gene sequences and possessed a mean DNA-DNA relatedness level of 94 %; they exhibited 16S rRNA gene sequence similarity levels of 96.8-98.2% to the type strains of recognized Herbaspirillum species. Phylogenetic analyses based on 16S rRNA gene sequences showed that isolates UMS-37T and UMS-40 formed a distinct phylogenetic lineage within the genus Herbaspirillum. DNA-DNA relatedness levels between isolates UMS-37T and UMS-40 and the type strains of some phylogenetically related Herbaspirillum species were in the range 3-56 %. On the basis of differences in phenotypic properties and phylogenetic distinctiveness and genomic data, isolates UMS-37T and UMS-40 were classified in the genus Herbaspirillum within a novel species, for which the name Herbaspirillum rhizosphaerae sp. nov. is proposed, with the type strain UMS-37T (=KCTC 12558T =CIP 108917T.