Tessaracoccus bendigoensis gen. nov., sp. nov., a Gram-positive coccus occurring in regular packages or tetrads, isolated from activated sludge biomass

An isolate of a Gram-positive bacterium, designated strain Ben 106(T), was obtained in pure culture by micromanipulation of a biomass sample obtained from a laboratory-scale sequencing batch reactor. This isolate grew axenica lly as cocci or clusters of cocci arranged in regular tetrads and was morph ologically similar to the dominant organism observed in the biomass. This m orphology resembled that of some Gram-positive and -negative bacteria and t he so-called 'G-bacteria' commonly seen in activated sludge samples. Strain Ben 106(T) is a non-motile, facultative anaerobe. It is oxidase-negative, catalase-positive and is capable of reducing nitrate. This organism can gro w between 20 and 37 degrees C, with an optimum temperature of 25 degrees C. The pH range for growth is between 6.0 and 9.0, with an optimum pH of 7.5. The isolate stained positively for intracellular polyphosphate granules. T he diagnostic diamino acid of the peptidoglycan is LL-diaminopimelic acid ( LL-A(2)pm) with a glycine moiety at position 1 of the peptide subunit, whic h characterizes the presence of a rare peptidoglycan (type A3-gamma'). Two menaquinones, MK-9(H-4) and MK-7(H-4), are present and the main cellular fa tty acid is 12-methyltetradecanoic acid. The G+C content is 74 mol%. From p henotypic characteristics and 16S rDNA sequence analysis, the isolate diffe red sufficiently from its closest phylogenetic relatives, namely Propioniba cterium propionicum, Propioniferax innocua, Friedmanniella antarctica, Lute ococcus japonicus and Microlunatus phosphovorus in the A1 subdivision of th e Gram-positive bacteria (i.e. Firmicutes with a high G+C content), suborde r Propionibacterineae, to be placed in a new genus, Tessaracoccus, as Tessa racoccus bendigoensis gen. nov., sp. nov. The type strain is Ben 106(T) (= ACM 5119(T)).