Polyphosphate-accumulating bacteria that were previously isolated from activated sludge and exhibited high phosphate removal activity were studied taxonomically and phylogenetically. These organisms were gram-positive, coccus-shaped, aerobic chemoorganotrophs that had a strictly respiratory type of metabolism in which oxygen was a terminal electron acceptor. They accumulated large amounts of polyphosphate under aerobic conditions. The major quinone was menaquinone MK-9(H4). The cell wall peptidoglycan contained LL-diaminopimelic acid. The guanine-plus-cytosine content of the DNA was 67.9 mol%. Our isolates were similar phenotypically and chemotaxonomically to Luteococcus japonicus, which was proposed recently as a new genus and species. However, our isolates differed from L. japonicus in cellular fatty acid composition and some other traits. A phylogenetic analysis based on 16S rRNA sequences showed 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-1T (T = type strain) should be assigned to a new genus and species, for which we propose the name Microlunatus phosphovorus.

A new gram-positive bacterium was isolated from activated sludge acclimated with sugar-containing synthetic wastewater. This organism, designated strain Y-104T (T = type strain), was a coccus-shaped, aerobic chemoorganotroph that had a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. This strain accumulates large amounts of polysaccharide in its cells. Strain Y-104T has the following chemotaxonomic characteristics: it contains menaquinone MK-8(H4), its DNA G+C content is 67.5 mol%, and it contains meso-diaminopimelic acid. No previously described high-G+ C-content gram-positive coccus contains both MK-8(H4) as a major quinone and meso-diaminopimelic acid in its cell wall. A phylogenetic analysis based on 16s rRNA sequences showed that strain Y-104T represents a line of descent distinct from those of previously described species of high-G+C-content gram-positive bacteria and that members of the genus Frankiu are the nearest neighbors. Therefore, we concluded that our isolate should be assigned to a new genus and species, for which we propose the name Microsphueru multipurtita. The type strain is strain Y-104.Activated sludge is a rich source of aerobic chemoorganotrophic bacteria which belong to various taxonomic and phylogenetic groups, and some of these organisms may not have been described yet. The community structure of activated sludge systems varies remarkably in response to the chemical nature of the wastewater and the operational conditions, and bacteria capable of rapid uptake and accumulation of substrates from the wastewater may predominate under substrate-limiting conditions, particularly when substrate addition is intermittent (for example, in batch treatment processes). The fact that activated sludges contain large amounts of reserve materials, such as glycogen, polyhydroxyalkanoates, and polyphosphate, under certain conditions suggests that there are bacterial species that have the ability to accumulate these reserve materials. Our recent study demonstrated that a new polyphosphateaccumulating gram-positive bacterium (22), for which we proposed the name Microlunatus phosphovonis (21), is present in activated sludge showing enhanced phosphate removal.The bacterial composition and capacity for polysaccharide accumulation of activated sludge treating carbohydrate-containing wastewater have been major subjects of study (27)(28)(29)(30)34). Early reports in the literature showed that large coccusshaped gram-positive bacteria constituted significant proportions of the bacterial flora of activated sludge loaded with carbohydrate-rich wastewater (28, 30), although no detailed taxonomic study of these gram-positive cocci was performed thereafter. Activated sludge cultured under batch operational conditions with intermittent addition of substrate containing glucose showed rapid substrate uptake and accumulated substrate as polysaccharide which was later consumed slowly for the synthesis of DNA, RNA, and protein (20). Accordingly, to elucidate the mechanism of selection o...

Approximately 30,000 fluorescent bacterial strains isolated from tomato, lettuce, eggplant, Chinese cabbage, and Japanese pepper plants at seven different locations in Hyogo Prefecture, were screened for plantgrowth-promoting (PGP) activity to induce disease resistance against bacterial wilt in tomato. The 37 strains that had higher PGP activity were subjected to molecular phylogenetic analyses using the sequences of the 16S rRNA, gyrB and rpoD genes. Most of the strains were identified as Pseudomonas fluorescens or its close relative, P. putida, while a few strains were grouped with more distantly related bacterial species such as Enterobacter and Stenotrophomonas. The phylogenetic relationships among tomato and lettuce isolates mostly coincided with the source locality and host plants, with a few exceptions. In contrast, isolates from Japanese pepper plants did not form their own cluster but represented several different bacterial species.