Rhizobium wuzhouense sp. nov., isolated from roots of Oryza officinalis.

Three bacterial isolates, designated W44T, W15 and W11, were isolated from the root of Oryza officinalis grown in Wuzhou, China. These isolates were Gram-negative, aerobic, motile and rod-shaped; demonstrated cellulase and urea activities; and formed cream-coloured colonies. The 16S rRNA gene sequence analysis indicated that the similarities between strain W44T and strains W15 and W11 were 100 %; all of them belonged to the genus Rhizobium and had the highest sequence similarity to Rhizobium rosettiformans W3T (98.7 %), followed by Rhizobium ipomoeae shin9-1T (98.2 %). Sequencing of housekeeping genes (recA, atpD, rpoB and glnA) of the novel isolates revealed similarities to members of established Rhizobium species to be less than 94.3 %. The values of DNA-DNA hybridization between strain W44T and the reference strains (R. rosettiformans W3T and R. ipomoeae shin9-1T) were 41.3 and 29.2 %, respectively. The major cellular fatty acid of strain W44T was summed feature 8 (C18 : 1ω9t and/or C18 : 1ω9c and/or C18 : 1ω7c). The polar lipid profile of strain W44T consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified lipids and two unidentified aminophospholipids. The G+C content of strain W44T was 62.4 mol%. In nodulation tests, none of the three strains could induce nodule formation in Glycine max, Phaseolus vulgaris or Medicago sativa. The nodulation gene (nodA), nitrogenase reductase gene (nifH) and virulence gene (virC) were not detected by PCR in these strains. Based on the above results and phenotypic features, a novel species, Rhizobium wuzhouense sp. nov., is proposed, with strain W44T (=CCTCC AB 2017179T=GDMCC 1.1257T=KCTC 62194T) as the type strain.