Rugamonas aquatica sp. nov. and Rugamonas rivuli sp. nov., isolated from a subtropical stream in PR China

Two Gram-stain-negative, catalase- and oxidase-positive, rod-shaped, motile strains (FT29W(T) and FT103W(T)) were isolated from a subtropical stream in PR China. Comparisons based on 16S rRNA gene sequences showed that strains FT29W(T) and FT103W(T) showed 98.7 and 98.6% 16S rRNA gene sequence similarities to Rugamonas rubra CCM 3730(T) as their closest neighbour, respectively. The calculated pairwise OrthoANlu values between strain R. rubra CCM 3730(T) and strains FT29W(T) and FT103W(T) were all 81.4%. The respiratory quinone of strains FT29W(T) and FT103W(T) was determined to be Q-8. The major fatty acids were C-16:1 omega 7c, C-16:0 and C-12:0. The polar lipids of strain FT103W(T) included phosphatidylethanolamine, phosphatidylglycerol and one unidentified phospholipid, but strain FT29W(T) did not contain phosphatidylglycerol. The genome sizes of strains FT29W(T) and FT103W(T) were 7.23 and 6.84 Mbp with G+C contents of 63.8 and 63.9 %, respectively. Although the pairwise OrthoANlu value between strains FT29W(T) and FT103W(T) was 95.2% which located in the transition region of species demarcation, the dissimilarities in the aspects of phenotypic, biochemical and genotypic characteristics supported these two strains should belong to the different species within genus Rugamonas, for which the names Rugamonas aquatica sp. nov. (type strain FT29W(T)=GDMCC 1.1643(T)=KACC 21316(T)) and Rugamonas rivuli sp. nov. (type strain FT103W(T)=GDMCC 1.1685(T) =KACC 21477(T)) are proposed.