Agrobacterium leguminum sp. Nov., isolated from nodules of phaseolus vulgaris in spain

Abstract

Two endophytic strains, coded MOVP5 and MOPV6, were isolated from nodules of Phaseolus vulgaris plants grown on agri-cultural soil in Southeastern Spain, and were characterized through a polyphasic taxonomy approach. Their 16S rRNA gene sequences showed 99.3 and 99.4 %, 98.9 and 99.6 %, and 99.0 and 98.7% similarity to ‘A. deltaense’ YIC 4121, A. radiobacter LGM 140, and A. pusense NRCPB10, respectively. Multilocus sequence analysis based on sequences of recA and atpD genes suggested that these two strains could represent a new Agrobacterium species with less than 96.5 % similarity to their closest relatives. PCR amplification of the telA gene, involved in synthesis of protelomerase, confirmed the affiliation of strains MOPV5 and MOPV6 to the genus Agrobacterium. Whole genome average nucleotide identity and digital DNA–DNA hybridization average values were less than 95.1 and 66.7 %, respectively, with respect to its closest related species. Major fatty acids in strain MOPV5 were C ω7c/C ω6c in summed feature 8, C cyclo ω8c, C and C 3-OH. Colonies were small to medium, pearl-white coloured on YMA at 28 °C and growth was observed at 10–42 °C, pH 5.0–10.0 and with 0.0–0.5 % (w/v) NaCl. The DNA G+C content was 59.9 mol%. These two strains differ from all other genomovars of Agrobacterium found so far, including those that have not yet given a Latin name. The combined genotypic, phenotypic and chemotaxonomic data support the classification of strain MOPV5 as representing a novel species of Agrobacterium, for which the name Agrobacterium leguminum sp. nov. is pro-posed. The type strain is MOPV5 (=CECT 30096=LMG 31779).