Microbiology of water and wastewater: Discovery of a new genus numerically dominant in municipal wastewater and antimicrobial resistances in numerically dominant bacteria from Oklahoma lakes.

Three bacterial isolates from municipal wastewater were investigated for their phenotypic, biochemical, and molecular characters. All strains were isolated from municipal wastewater, and the type strain, NRS1T, was isolated as a numerically dominant heterotrophic bacterium. The isolates NRS1T, NRS30, and NRS32 were Gram-negative, catalase and oxidase positive, nonmotile, non spore-forming, yellow to orange pigmented rods. Pigments were of the carotenoid-type, and no flexirubin-type pigments were detected. All strains degraded gelatin, starch, esculin, casein, and weakly degraded DNA. None degraded cellulose, chitin, agar, urea, pectin, alginate, uric acid, xanthine, or hypoxanthine. Indole was produced by all strains. All strains were methyl red and Voges-Proskauer negative, and nitrate was not reduced. Pyruvate was observed as an end-product from growth on unbuffered glucose. The predominant respiratory quinone was menaquinone MK-6. The DNA base composition was 31 mole % G+C. 16S rRNA gene sequence analysis indicated that these three strains, as well as two uncharacterized strains, MRS7 and MRS14, were members of the Chryseobacterium-Bergeyella-Riemerella branch of the family Flavobacteriaceae. This bacterium could not be ascribed to any known genus by cellular fatty acid analysis or BIOLOG analysis. All strains were phylogenetically unaffiliated with any described genus from the 16S ribosomal gene sequence analysis. It is therefore proposed that the unknown bacterium be classified in a new genus Cloacibacterium gen. nov., as Cloacibacterium normanensis gen. nov. sp. nov. The type species of the genus Cloacibacterium is Cloacibacterium normanensis strain NRS1T (=ATCC BAA-825T) (=DSM 15886T) (=CCUG 46293T) (=CIP 108613 T). The GenBank accession number for the 16S gene sequence of strain NRS1T is AJ575430. The habitat for Cloacibacterium is municipal wastewater, where it was discovered as a numerically dominant species