Silvimonas iriomotensis sp. nov. and Silvimonas amylolytica sp. nov., new members of the class Betaproteobacteria isolated from the subtropical zone in Japan.

The taxonomic positions of two bacterial strains, ir6-1(T) and ir6-4(T), isolated from soil collected in Iriomote Island in Japan, were determined by using a polyphasic taxonomic approach. The strains were facultatively anaerobic, motile and Gram-stain-negative rods and their optimum pH for growth was pH 4.0. Their major respiratory quinone was ubiquinone-8 and the predominant cellular fatty acids were C(14 : 0), C(16 : 0), C(16 : 1)omega7c and C(18 : 1)omega7c. The G+C content of the genomic DNA of ir6-1(T) and ir6-4(T) was 59.9 and 57.5 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strains clustered with the genus Silvimonas in the class Betaproteobacteria. DNA-DNA similarities were lower than 53 % among ir6-1(T), ir6-4(T) and Silvimonas terrae NBRC 100961(T), and these strains could be differentiated from each other by several phenotypic characters. Based on these results, we propose the emendation of the genus Silvimonas and inclusion of two novel species, Silvimonas iriomotensis sp. nov. (type strain ir6-1(T)=NBRC 103188(T) =CGMCC 1.8859(T) =KCTC 22513(T)) and Silvimonas amylolytica sp. nov. (ir6-4(T) =NBRC 103189(T) =CGMCC 1.8860(T) =KCTC 22514(T)).