Rhizobium capsici sp. nov., isolated from root tumor of a green bell pepper (Capsicum annuum var. grossum) plant

A novel, Gram-staining-negative, rod-shaped, aerobic and motile bacterium, designated strain CC-SKC2T, was isolated from the root tumor of a green bell pepper (Capsicum annuum var. grossum) plant in Taiwan. Cells were positive for oxidase and catalase activities and exhibited growth at 25–37 °C, pH 4.0–9.0 and tolerated NaCl concentrations up to 4.0 % (w/v). Strain CC-SKC2T is able to trigger nodulation in soybean (Glycine max Merr.), but not in Capsicum annuum var. grossum, red bean (Vigna angularis), sesbania (Sesbania roxburghii Merr.) or alfalfa (Medicago varia Martin.). The novel strain shared highest 16S rRNA gene sequence similarity to Rhizobium rhizoryzae KCTC 23652T and Rhizobium straminoryzae CC-LY845T (both 97.5 %) followed by Rhizobium lemnae L6-16T (97.3 %), Rhizobium pseudoryzae KCTC 23294T (97.1 %), and Rhizobium paknamense NBRC 109338T (97.0 %), whereas other Rhizobium species shared <96.7 % similarity. The DNA–DNA relatedness values of strain CC-SKC2T with R. rhizoryzae KCTC 23652T, R. pseudoryzae KCTC 23294T and R. paknamense NBRC 109338T were 11.4, 17.2 and 17.0 %, respectively (reciprocal values were 11.1, 28.3 and 24.0 %, respectively). Phylogenetic analysis based on 16S rRNA, atpD and recA genes revealed a distinct taxonomic position attained by strain CC-SKC2T with respect to other Rhizobium species. The major fatty acids in strain CC-SKC2T were C16:0, C19:0 cyclo ω8c, C14:0 3-OH and/or C16:1 iso I and C18:1ω7c and/or C18:1ω6c. The polyamine pattern showed predominance of spermidine and moderate amounts of sym-homospermidine. The predominant quinone system was ubiquinone (Q-10) and the DNA G+C content was 60.5 mol%. On the basis of polyphasic taxonomic evidence presented here, strain CC-SKC2T is proposed to represent a novel species within the genus Rhizobium, for which the name Rhizobium capsici sp. nov. is proposed. The type strain is CC-SKC2T (=BCRC 80699T = JCM 19535T).