MICROLUNATUS PHOSPHOVORUS GEN-NOV, SP-NOV, A NEW GRAM-POSITIVE POLYPHOSPHATE-ACCUMULATING BACTERIUM ISOLATED FROM ACTIVATED-SLUDGE

Polyphosphate-accumulating bacteria that were previously isolated from activated sludge and exhibited high phosphate removal activity were s tudied taxonomically and phylogenetically. These organisms were grampo sitive, coccus-shaped, aerobic chemoorganotrophs that had a strictly r espiratory type of metabolism in which oxygen was a terminal electron acceptor. They accumulated large amounts of polyphosphate under aerobi c conditions. The major quinone was menaquinone MK-9(H,). The cell wal l peptidoglycan contained LL-diaminopimelic acid. The guanine-plus-cyt osine content of the DNA was 67.9 mol%. Our isolates were similar phen otypically and chemotaxonomically to Luteococcus japonicus, which was proposed recently as a new genus and species. However, our isolates di ffered from L. japonicus in cellular fatty acid composition and some o ther traits. A phylogenetic analysis based on 16S rRNA sequences showe d that our isolate differ from the genus Luteococcus and other genera belonging to the high-G+C-content gram-positive group. Accordingly, we concluded that our strain NM-1(T) (T = type strain) should be assigne d to a new genus and species, for which we propose the name Microlunat us phosphovorus.