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Rhizobium paknamense sp. nov., isolated from lesser duckweeds (Lemna aequinoctialis)
Date Issued
October 1, 2013
Type
Article
Abstract
A Gram-stain-negative, rod-shaped bacterium was isolated and designated strain L6-8T during a study of endophytic bacterial communities in lesser duckweed (Lemna aequinoctialis). Cells of strain L6-8T were motile with peritrichous flagella. The analysis of the nearly complete 16S rRNA gene sequence indicated that strain L6-8T was phylogenetically related to species of the genus Rhizobium. Its closest relatives were Rhizobium borbori DN316T (97.6 %), Rhizobium oryzae Alt 505T (97.3 %) and Rhizobium pseudoryzae J3-A127T (97.0 %). The sequence similarity analysis of housekeeping genes recA, glnII, atpD and gyrB showed low levels of sequence similarity (,91.5 %) between strain L6-8T and other species of the genus Rhizobium with validly published names. The pH range for growth was 4.0-9.0 (optimum 6.0-7.0), and the temperature range for growth was 20-45 °C (optimum 30 °C). Strain L6-8T tolerated NaCl up to 2% (w/v) (optimum 1% NaCl). The predominant components of cellular fatty acids were C19: 0 cyclo ω8c (31.32 %), summed feature 8 (C18: 1ω7c and/or C18: 1ω6c; 25.39 %) and C16: 0 (12.03 %). The DNA G+C content of strain L6-8T was 60.4 mol% (Tm). nodC and nifH were not amplified in strain L6-8T. DNA-DNA relatedness between strain L6-8T and R. borbori DN316T, R. oryzae Alt505T and R. pseudoryzae J3-A127T was between 11.2 and 18.3 %. Based on the sequence similarity analyses, phenotypic, biochemical and physiological characteristics and DNA-DNA hybridization, strain L6-8T could be readily distinguished from its closest relatives and represents a novel species of the genus Rhizobium, for which the name Rhizobium paknamense sp. nov. is proposed. The type strain is L6-8T (=NBRC 109338T=BCC 55142T). © 2013 IUMS.
Citation
International Journal of Systematic and Evolutionary Microbiology, 63(PART10), 3823-3828, 2013