Elstera litoralis gen. nov., sp nov., isolated from stone biofilms of Lake Constance, Germany

An alphaproteobacterium, strain Dia-1(T), was isolated from algae-dominated biofilms on stones from the littoral zone of Lake Constance, Germany. This bacterium was isolated after initial enrichment in spent medium obtained after growth of a diatom culture. Numerous sugars and some organic acids and alcohols served as growth substrates. The bacterium grew slowly, was strictly aerobic but microaerophilic, and did not grow in cultures shaken under air. 16S rRNA gene sequence analysis indicated that strain Dia-1(T) was distantly related to representatives of the genera Azospirillum (90-91% sequence similarity), Skermanella (88-89 %), Rhodocista (87-88 %) and Dongia (88-89% sequence similarity). Based on this sequence comparison, on phenotypic characterization including substrate utilization patterns, and comparison of cellular fatty acids, quinones, polar lipids and polyamines, this isolate was found to be substantially different from the genera mentioned above. On the basis of these results, a novel genus and species is proposed for this strain. The name Elstera litoralis gen. nov., sp. nov. is suggested, with strain Dia-1(T) (=DSM 19532(T)=LMG 24234(T)) as the type strain of the type species.