Oharaeibacter diazotrophicus gen. nov., sp nov., a diazotrophic and facultatively methylotrophic bacterium, isolated from rice rhizosphere

Abstract

A novel facultatively methanol-utilizing bacterial strain, SM30(T), was isolated from rice rhizosphere. Strain SM30(T) was Gram-stain-negative, aerobic, motile, short rods, and grew optimally at pH 7 and at 28 degrees C. It could tolerate 0 to 2%(w/v) NaCl. Based on 16S rRNA gene sequence comparisons, strain SM30(T) was most closely related to Pleomorphomonas oryzae DSM 16300(T), with a low similarity of 94.17 %. One of the lanthanide metals, lanthanum, could enhance its growth slightly on methanol. Phylogenetic trees, based on the mxaF, xoxF and cpn60 genes of SM30(T) showed its distinct phylogenetic position with respect to species with validly published names. Polymerase chain reaction (PCR) amplification of the nifH and growth on nitrogen-free medium indicated that strain SM30(T) is a diazotroph. The major cellular fatty acids were summed feature 8 (containing 18:1 omega 7c and 18:1 omega 6c) and cyclo 19:0 omega 8c. The major quinone was ubiquinone 10. The DNA G+C content was 74.6 mol%. Based on the genotypic and phenotypic characteristics, strain SM30(T) represents a novel genus and species, for which the name Oharaeibacter diazotrophicus gen. nov., sp. nov. is proposed with the type strain SM30(T) (= NBRC 111955(T) = DSM 102969(T)).