Rhizobium halotolerans sp. nov., Isolated from chloroethylenes contaminated soil.

The strain designated as AB21(T) 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 123(T) (97.4 %), Rhizobium yanglingense SH 22623(T) (97.2 %), Rhizobium gallicum R 602sp(T) (97.1 %), Rhizobium alamii GBV 016(T) (97.0 %), and Rhizobium monogolense USDA 1844(T) (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 C(18:1) ω7c/C(18:1) ω6c), C(19:0) cyclo ω8c, and C(16:0). The G+C molar content is 62.5 mol%. Based on the polyphasic analysis, strain AB21(T) 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 AB21(T) (=KEMC 224-056(T) = JCM 17536(T)).