Pseudomonas guariconensis sp. nov., isolated from rhizospheric soil.

We isolated a bacterial strain designated PCAVU11(T) in the course of a study of phosphate-solubilizing bacteria occurring in rhizospheric soil of Vigna unguiculata (L.) Walp. in Guárico state, Venezuela. The 16S rRNA gene sequence had 99.2 % sequence similarity with respect to the most closely related species, Pseudomonas taiwanensis, and 99.1 % with respect to Pseudomonas entomophila, Pseudomonas plecoglossicida and Pseudomonas monteilii, on the basis of which PCAVU11(T) was classified as representing a member of the genus Pseudomonas. Analysis of the housekeeping genes rpoB, rpoD and gyrB confirmed the phylogenetic affiliation and showed sequence similarities lower than 95 % in all cases with respect to the above-mentioned closest relatives. Strain PCAVU11(T) showed two polar flagella. The respiratory quinone was Q9. The major fatty acids were 16 : 0 (25.7 %), 18 : 1ω7c (20.4 %), 17 : 0 cyclo (11.5 %) and 16 : 1ω7c/15 : 0 iso 2-OH in summed feature 3 (10.8 %). The strain was oxidase-, catalase- and urease-positive, the arginine dihydrolase system was present but nitrate reduction, β-galactosidase production and aesculin hydrolysis were negative. Strain PCAVU11(T) grew at 44 °C and at pH 10. The DNA G+C content was 61.5 mol%. DNA-DNA hybridization results showed values lower than 56 % relatedness with respect to the type strains of the four most closely related species. Therefore, the results of genotypic, phenotypic and chemotaxonomic analyses support the classification of strain PCAVU11(T) as representing a novel species of the genus Pseudomonas, which we propose to name Pseudomonas guariconensis sp. nov. The type strain is PCAVU11(T) ( = LMG 27394(T) = CECT 8262(T)).