Summary auto-generated
Researchers isolated a new Gram-positive bacterium, strain Lg2T, from an enhanced biological phosphorus removal (EBPR) activated sludge reactor. The organism is a slow-growing, non-spore-forming coccus that accumulates intracellular glycogen—reaching up to 8.4% of dry cell weight—but does not accumulate polyphosphate. Characterization revealed the bacterium contains meso-diaminopimelic acid (meso-DAP) in its cell wall, a high genomic G+C content of 70.5 mol%, and menaquinone-9(H₄) as its major quinone. 16S rRNA gene phylogenetic analysis placed it within the high G+C Gram-positive bacteria group, showing 93% sequence similarity to Microlunatus phosphovorus and 92% to Friedmanniella antarctica. Despite morphological similarities to these relatives, strain Lg2T differs in peptidoglycan type, fatty acid composition, substrate utilization profile, and G+C content. Based on these phenotypic and genotypic differences, the authors propose a new genus and species: Micropruina glycogenica, with strain Lg2T designated as the type strain.
Key findings
- A new Gram-positive bacterium, Micropruina glycogenica gen. nov., sp. nov., was isolated from activated sludge and characterized as a glycogen-accumulating coccus capable of storing up to 8.4% glycogen by dry cell weight.
- The organism phylogenetically belongs to the high G+C Gram-positive bacteria, most closely related to Microlunatus phosphovorus (93% 16S rRNA similarity) and Friedmanniella antarctica (92% similarity).
- Strain Lg2T is distinguishable from related species by its meso-DAP peptidoglycan type (compared to L-DAP in relatives), unique fatty acid profile, G+C content of 70.5 mol%, and different carbon utilization patterns.
- The bacterium is a slow-growing mesophile (optimum 30°C) that accumulates glycogen but lacks polyphosphate-accumulation ability, suggesting it represents a distinct metabolic strategy in EBPR microbial communities.
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Abstract
A new Gram-positive non-spore-forming bacterium, strain Lg2(T), was isolated from an activated sludge reactor showing enhanced biological phosphorus removal activity. The new isolate was a slowly growing organism and was capable of accumulating large amounts of intracellular glycogen from substrate taken up. Both oxidase and catalase were produced. The new isolate contained meso-diaminopimelic acid (DAP) in the cell wall. Complex fatty acid patterns with iso-C(14:0), anteiso-C(15:0), C(16:0), iso-C(16:0) and four other minor saturated or unsaturated straight-chain fatty acids were detected. The isolate contained a high genomic G+C content (70.5 mol%). Phylogenetic analysis based on the 16S rRNA gene sequence placed the isolate in the high G+C Gram-positive group with Microlunatus phosphovorus and Friedmanniella antarctica as the closest relatives (sequence similarities are 93 and 92%, respectively). These three organisms shared common features in morphology, but strain Lg2(T) could be differentiated from the other species by its peptidoglycan type (meso-DAP), fatty acid composition, carbon source utilization profile and G+C content. On the basis of these findings, it is proposed that a new genus and species, Micropruina glycogenica, should be created for the new isolate; the type strain is strain Lg2(T) (=JCM 10248(T)).