Duganella sacchari sp. nov. and Duganella radicis sp. nov., two novel species isolated from rhizosphere of field-grown sugar cane.

Two strains, designated Sac-22(T) and Sac-41(T), were isolated from rhizosphere soil and rhizoplane of field-grown sugar cane clone Co86032. Comparative 16S rRNA gene sequence analysis showed a clear affiliation of these two bacteria with the class Betaproteobacteria, their closest relatives being Pseudoduganella violaceinigra and Duganella zoogloeoides with 16S rRNA gene sequence pairwise similarities of 96.4-97.2 % to the two novel strains. Strains Sac-22(T) and Sac-41(T) shared a 16S rRNA gene sequence similarity value of 97.6 %. Cells of the two strains were Gram-reaction-negative, aerobic, motile and rod-shaped. Ubiquinone (Q-8) was the respiratory quinone and the predominant polar lipids consisted of phosphatidylglycerol and phosphatidylethanolamine. The main cellular fatty acids were C16 : 0, C16 : 1ω7c/iso-C15 : 0 2-OH, C17 : 0 cyclo, C10 : 0 3-OH and C12 : 0. The DNA G+C content of the genomic DNA was 56.4 mol% for strain Sac-22(T) and 54.9 mol% for strain Sac-41(T). Based on the results of 16S rRNA gene sequence analysis and physiological and biochemical characterization, that differentiated strains Sac-22(T) and Sac-41(T) from all recognized species of the genus Duganella, it was concluded that strains represent two novel species in the genus Duganella for which the names Duganella sacchari sp. nov. (type strain Sac-22(T) = KCTC 22381(T) = NCIMB 14475(T)) and Duganella radicis sp. nov. (type strain Sac-41(T) = KCTC 22382(T) = NCIMB 14476(T)) are proposed.