Duganella albus sp. nov., Duganella aquatilis sp. nov., Duganella pernnla sp. nov. and Duganella levis sp. nov., isolated from subtropical streams in China

Six Gram-stain-negative, catalase- and oxidase-positive, rod-shaped and motile strains (FT9W(T), FT25W, FT26W(T), FT109W(T), FT134W and CY42W(T)) were isolated from subtropical streams in China. Comparisons based on 16S rRNA gene sequences showed that the six strains shared similarities of less than 98.1 % with other species within the family Oxalobacteraceae and formed two separately distinct clades in phylogenetic trees. The 16S rRNA gene sequence similarities between strains FT9W(T) and FT25W, and between strains FT109W(T) and FT134W were both 99.7 %. The genome sizes of strains FT9W(T), FT25W, FT26W(T), FT109W(T), FT134W and CY42W(T) were 6.45, 6.45, 6.54, 6.43, 6.52 and 6.74 Mbp with G+C contents of 64.0, 64.0, 63.8, 63.2, 63.2 and 62.5%, respectively. The calculated pairwise average nucleotide (ANI) values among the six strains and other related species were less than 93.9%, except that the values were 99.9% between strains FT9W(T) and FT25W, 98.2 % between strains FT109W(T) and FT134W, and 95.0 and 95.1 % between strain FT26W(T) and strains FT9W(T) and FT25W, respectively. However, strain FT26W(T) shared 16S rRNA gene sequence similarities of only 98.3 and 98.2% with FT9W(T) and FT25W, respectively. The respiratory quinone of the six strains was determined to be Q-8. The major fatty acids were C-16:1 omega 7c, C-16:0 and C-12:0. The predominant polar lipids included phosphatidylethanolamine and phosphatidylglycerol. Considering the phenotypic, biochemical, genotypic and ANI data, strains FT9W(T) and FT25W, and FT109W(T) and FT134W may belong to the same species, respectively. Although the pairwise ANI values between strain FT26W(T) and each of strains FT9W(T) and FT25W were located in the transition region of species demarcation, the dissimilarities among them indicated that strain FT26W(T) could represent an independent novel species. The reconstructed phylogenomic tree based on a concatenation of 92 core genes showed that the six strains clustered closely with Duganella sacchari Sac-22(T) and Duganella radicis KCTC 22382(T), and supported that these six strains belong to the genus Duganella. The names Duganella albus sp. nov. (type strain FT9W(T)=GDMCC 1.1637(T)=KACC 21313(T)), Duganella aquatilis sp. nov. (type strain FT26W(T)=GDMCC 1.1641(T)=KACC 21315(T)), Duganella pernnla sp. nov. (type strain FT109W(T)=GDMCC 1.1688(T)=KACC 21480(T)) and Duganella levis sp. nov. (type strain CY42W(T)=GDMCC 1.1673(T)=KACC 21465(T)) are proposed.