Rhizobium straminoryzae sp. nov., isolated from the surface of rice straw

Abstract

An aerobic, Gram-stain-negative, rod-shaped bacterium, designated strain CC-LY845T, was isolated from the surface of rice straw in Taiwan. Cells were non-motile, and no flagellum was detected. Comparison of 16S rRNA gene sequences indicated that the strain was phylogenetically related to species of the genus Rhizobium , with closest similarity to Rhizobium pseudoryzae KCTC 23294T (97.6 %), R. rhizoryzae KCTC 23652T (97.0 %) and R. oryzae LMG 24253T (96.7 %); other species showed lower levels of similarity (<96.6 %). The DNA–DNA relatedness of strain CC-LY845T and R. pseudoryzae KCTC 23294T was 34.8±3.1 % (reciprocal value 39.2±2.2 %). Phylogenetic analysis based on the housekeeping atpD and recA genes showed that the novel strain could be distinguished from R. pseudoryzae KCTC 23294T (92.7 and 91.5 %, respectively) and other species of the genus Rhizobium . The temperature range for growth was 25–42 °C, the pH range was 5.0–9.0 and NaCl concentrations up to 4.0 % (w/v) were tolerated. Strain CC-LY845T did not form nodules on four different legumes, and the nodD and nifH genes were not detected by PCR. The major fatty acids were C16 : 0 and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c). The polyamine pattern of strain CC-LY845T showed spermidine and putrescine as major polyamines. The predominant quinone system was ubiquinone 10 (Q-10). The DNA G+C content was 68.3±2.4 mol%. Base on its phylogenetic, phenotypic and chemotaxonomic features, strain CC-LY845T is proposed to represent a novel species within the genus Rhizobium , for which the name Rhizobium straminoryzae sp. nov. is proposed. The type strain is strain CC-LY845T ( = BCRC 80698T = JCM 19536T).