Dickeya aquatica sp nov., isolated from waterways

Pectinolytic Gram-negative bacteria were isolated from different waterways in the UK and Finland. Three strains (174/2(T), 181/2 and Dw054) had the same 16S rRNA gene sequences which shared 99% sequence similarity to species of the genus Dickeys, and a phylogeny of related genera confirmed attribution to this genus. Fatty acid profile analysis of all three strains found a high proportion of C-16:1 omega 7c/C-16:1 omega 7c and C-16:0 fatty acids, and library profile searches found closest matches to Dickeya chrysanthemi. Production of a concatenated phylogeny using six loci, recA, gapA, atpD, gyrB, infB and rpoB, provided a high-resolution phylogeny which placed strains 174/2(T) and 181/2 as a distinct clade, separated from the other species of the genus Dickeya by a relatively long branch-length. DNA-DNA hybridization analysis with a limited number of reference species also supported the distinctiveness of strains 174/2(T) and 181/2 within the genus Dickeya. All three strains could be phenotypically distinguished from other species of the genus by fermentation of melibiose and raffinose but not D-arabinose or mannitol. The name Dickeys aquatica sp. nov. is proposed for the new taxon; the type strain is 174/2(T) (=NCPPB 4580(T)=LMG 27354(T)).