Rhizobium halotolerans sp. nov., Isolated from Chloroethylenes Contaminated Soil

The strain designated as AB21T was isolated from chloroethylenes contaminated soil. Cells are gram-negative, aerobic, non-spore-forming, and motile rods. Phylogenetic analysis based on 16S rRNA gene sequence showed that it belonged to the genus Rhizobium, and was closely related to Rhizobium sullae IS 123T (97.4 %), Rhizobium yanglingense SH 22623T (97.2 %), Rhizobium gallicum R 602spT (97.1 %), Rhizobium alamii GBV 016T (97.0 %), and Rhizobium monogolense USDA 1844T (97.0 %). It showed less than 97 % identity with the remaining Rhizobium species. This novel isolate grew optimally at 25–37 °C (optimum, 30 °C) and pH 6–9 (optimum, pH 8.0). It grew in the presence of 0–4 % (w/v) NaCl, tolerating a 4 % (w/v) NaCl. DNA–DNA hybridization experiment shows less than 53 % binding with closely related Rhizobium. Predominant quinone is ubiquinone (Q-10). The major fatty acids were summed feature 8 (composed of C18:1ω7c/C18:1ω6c), C19:0 cyclo ω8c, and C16:0. The G+C molar content is 62.5 mol%. Based on the polyphasic analysis, strain AB21T is referred to be a novel species of the genus Rhizobium for which the name Rhizobium halotolerans sp. nov. is proposed. The type strain is AB21T (=KEMC 224-056T = JCM 17536T).