Rhizobium smilacinae sp. nov., an endophytic bacterium isolated from the leaf of Smilacina japonica

Abstract

During a study of endophytic bacteria from traditional Chinese medicinal plants, a bacterial strain, designated PTYR-5(T), was isolated from the leaf of Smilacina japonica A. Gray collected from Taibai Mountain in Shaanxi Province, north-west China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain PTYR-5(T) is a member of the genus Rhizobium, exhibiting the highest sequence similarities to R. cellulosilyticum LMG 23642(T) (97.2%), R. huautlense LMG 18254(T) (97.2%) and R. alkalisoli CCBAU 01393(T) (97.1%). The levels of 16S rRNA gene sequence similarity with respect to other Rhizobium species with validly published names were less than 97.0%. Phylogenies of the housekeeping genes atpD, recA and glnII confirmed its distinct position, showing low similarity with respect to those of recognized Rhizobium species (no more than 94.1, 90.0 and 88.0% similarity, respectively). The DNA-DNA relatedness values of strain PTYR-5(T) with R. cellulosilyticum LMG 23642(T), R. huautlense LMG 18254(T) and R. alkalisoli CCBAU 01393(T) were 33.6, 21.4 and 29.5 %, respectively. Based on phenotypic, phylogenetic and genotypic data, strain PTYR-5(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium smilacinae sp. nov. is proposed. The type strain is PTYR-5(T) (=CCTCC AB 2013016(T)=KCTC 32300(T)=LMG 27604(T)).