Rhizobium paknamense sp. nov., isolated from lesser duckweeds (Lemna aequinoctialis)

C. Kittiwongwattana, C. Thawai
2013 International Journal of Systematic and Evolutionary Microbiology  
A Gram-stain-negative, rod-shaped bacterium was isolated and designated strain L6-8 T during a study of endophytic bacterial communities in lesser duckweed (Lemna aequinoctialis). Cells of strain L6-8 T were motile with peritrichous flagella. The analysis of the nearly complete 16S rRNA gene sequence indicated that strain L6-8 T was phylogenetically related to species of the genus Rhizobium. Its closest relatives were Rhizobium borbori DN316 T (97.6 %), Rhizobium oryzae Alt 505 T (97.3 %) and
more » ... izobium pseudoryzae J3-A127 T (97.0 %). The sequence similarity analysis of housekeeping genes recA, glnII, atpD and gyrB showed low levels of sequence similarity (,91.5 %) between strain L6-8 T 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 6C (optimum 30 6C). Strain L6-8 T tolerated NaCl up to 2 % (w/v) (optimum 1 % NaCl). The predominant components of cellular fatty acids were C 19 : 0 cyclo v8c (31.32 %), summed feature 8 (C 18 : 1 v7c and/or C 18 : 1 v6c; 25.39 %) and C 16 : 0 (12.03 %). The DNA G+C content of strain L6-8 T was 60.4 mol% (T m ). nodC and nifH were not amplified in strain L6-8 T . DNA-DNA relatedness between strain L6-8 T and R. borbori DN316 T , R. oryzae Alt505 T and R. pseudoryzae J3-A127 T was between 11.2 and 18.3 %. Based on the sequence similarity analyses, phenotypic, biochemical and physiological characteristics and DNA-DNA hybridization, strain L6-8 T 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 L6-8 T (5NBRC 109338 T 5BCC 55142 T ).
doi:10.1099/ijs.0.051888-0 pmid:23687054 fatcat:i2gspi5edzf3nn43u26unpehqm