The species of the genus ''Aquabacterium'' are motile,

rod-shaped Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria (and archae ...

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

oxidase In biochemistry, an oxidase is an oxidoreductase (any enzyme that catalyzes a redox reaction) that uses dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen peroxid ...

-positive,

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting ...

-negative

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

which were isolated from drinking water

biofilms A biofilm is a syntrophic community of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymer ...

in Berlin. Identified species include '' Aquabacterium citratiphilum'', '' Aquabacterium parvum'', and '' Aquabacterium commune''. Three bacterial strains isolated from biofilms of the Berlin drinking water system were characterized with respect to their morphological and physiological properties and their taxonomic position. Phenotypically, the bacteria investigated were motile, Gram-negative rods, oxidase-positive and catalase-negative, and contained polyalkanoates and polyphosphate as storage polymers. They displayed a microaerophilic growth behaviour and used oxygen and nitrate as electron acceptors, but not nitrite, chlorate, sulfate, or ferric iron. The substrates metabolized included a broad range of organic acids, but no carbohydrates at all. The three species can be distinguished from each other by their substrate use, ability to hydrolyse urea and casein, cellular protein patterns, and growth on nutrient-rich media, as well as their temperature, pH, and NaCl tolerances. Phylogenetic analysis, based on 16S rRNA gene sequence comparison, revealed that the isolates are affiliated to the beta 1-subclass of Proteobacteria. The isolates constitute three new species with internal levels of DNA relatedness ranging from 44.9 to 51.3%. It is proposed that a new genus, ''Aquabacterium'' gen. nov., should be created, including ''Aquabacterium citratiphilum'' sp. nov.,'' Aquabacterium parvum'' sp. nov., and ''Aquabacterium commune'' sp. nov. The type species of the new genus is ''Aquabacterium commune''.

References

Bacteria genera Comamonadaceae {{betaproteobacteria-stub