Rhizobium skierniewicense sp. nov., isolated from tumours on chrysanthemum and cherry plum

Three isolates of Gram-negative, rod-shaped, non-spore-forming bacteria were recovered from galls on chrysanthemum (Chrysanthemum L.; Ch11^T, Ch12) and cherry plum (Prunus cerasifera var. divaricata; AL9.3). All three isolates were able to cause crown galls on various plant species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the three isolates were probably identical (100% sequence similarity) and closely related to Rhizobium rubi (99.6 %), Rhizobium radiobacter (98.7 %) and Rhizobium larrymoorei (98.1 %). Similar analysis based on the housekeeping genes glnA, gyrB and rpoB also indicated that the novel isolates were identical and closely related to R. rubi. The major cellular fatty acids of strain Ch11^T were C_18 : 1ω7c (62.1 %), summed feature 2 (comprising C_12 : 0 aldehyde, iso-C_16 : 1 I and/or C_14 : 0 3-OH; 10.8 %), summed feature 3 (comprising C_16 : 1ω7c and/or iso-C_15 : 0 2-OH; 7.7 %) and C_10 : 0 3-OH (7.5 %). However, the DNA–DNA relatedness between Ch11^T and R. rubi LMG 156^T was only 48 % and, unlike phylogenetically related established Rhizobium species, the novel isolates were able to utilize β-hydroxybutyric acid but not l-fucose. Based on the phylogenetic and phenotypic evidence, the isolates are considered to represent a single novel species of the genus Rhizobium, for which the name Rhizobium skierniewicense sp. nov. is proposed; the type strain is Ch11^T ( = LMG 26191^T = CFBP 7420^T).