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Rhizobium lemnae sp. nov., a bacterial endophyte of Lemna aequinoctialis
Date Issued
January 1, 2014
Type
Article
Abstract
Bacterial strain L6-16T was isolated from Lemna aequinoctialis. Cells were Gram-stain-negative, rod-shaped and motile with monopolar flagella. The phylogenetic analysis of its nearly complete 16S rRNA gene sequence revealed that strain L6-16T was a member of the genus Rhizobium. Its closest relative was Rhizobium tarimense PL-41T with a 16S rRNA gene sequence similarity value of 98.3 %. Sequence similarity analysis of the housekeeping recA and atpD genes showed low levels of sequence similarity (<93.9 %) between strain L6-16T and other species of the genus Rhizobium. Strain L6-16T was able to grow between pH 5 and 11 (optimum 7.0) and at temperatures ranging from 20 to 41 °C (optimum 30 °C). It tolerated NaCl up to 1 % (w/v) (optimum 0.5 %). C18: 1ω7c and/or C18: 1ω6c (summed feature 8; 79.5 %) were found as predominant cellular fatty acids. The DNA G+C content of strain L6-16T was 58.1 mol% (Tm). Based on low levels of DNA-DNA relatedness, strain L6-16Twas distinct from members of phylogenetically related species including R. tarimense PL-41T (38.3±0.8 %), Rhizobium rosettiformans W3T (6.9±0.4 %) and Rhizobium pseudoryzae J3-A127T (12.3±0.6 %). Strain L6-16T was unable to nodulate the roots of Phaseolus vulgaris, and nodC and nifH genes were not detected. The results obtained from phylogenetic analyses, phenotypic characterization and DNA-DNA hybridization indicated that strain L6-16Trepresents a novel species of the genus Rhizobium, for which the name Rhizobium lemnae sp. nov. is proposed. The type strain is L6-16T (=NBRC 109339T=BCC 55143T). © 2014 IUMS.
Citation
International Journal of Systematic and Evolutionary Microbiology, 64(PART 7), 2455-2460, 2014