Sphingobium chungangianum sp. nov., isolated from rhizosphere of Pinus koraiensis.

A novel Gram-staining negative, yellow-pigmented, non-motile, aerobic and rod-shaped bacterium, designated MAH-11, was isolated from rhizosphere of Pinus koraiensis and was characterised by using a polyphasic taxonomic approach. The colonies were smooth, circular and 0.3-1.0 mm in diameter when grown on R2A agar for 3 days. The strain was positive for both catalase and oxidase tests. Optimum growth temperature and pH were 28-30 °C and 7.0, respectively. Cell growth occurs on R2A agar, nutrient agar, Luria-Bertani agar and tryptone soya agar but not on MacConkey agar. The novel strain was found to be able to hydrolyse esculin but not casein, gelatin, starch, L-tyrosine, DNA, L-arginine, urea, Tween 20 and Tween 80. On the basis of 16S rRNA gene sequence analysis, strain MAH-11 belongs to the genus Sphingobium and is closely related to Sphingobium quisquiliarum P25 (98.1%), Sphingobium vermicomposti VC-230 (97.8%), Sphingobium mellinum WI4 (97.5%), Sphingobium barthaii KK22 (97.2%) and Sphingobium fuliginis TKP (97.2%). In DNA-DNA hybridization tests, the DNA relatedness values between strain MAH-11 and its close phylogenetic neighbors were below 45.0%. The DNA G+C content was 64.5 mol% and the predominant respiratory quinone was identified as ubiquinone-10. The major cellular fatty acids were summed feature 8 (Cω7c and/or Cω6c), summed feature 3 (Cω7c and/or Cω6c) and C. The DNA-DNA hybridization results in combination with chemotaxonomic and physiological data demonstrated that strain MAH-11 represents a novel species within the genus Sphingobium, for which the name Sphingobium chungangianum is proposed. The type strain is MAH-11 (= KACC 19836 = CGMCC 1.13749).