Summary auto-generated
Researchers characterized a novel bacterium isolated from the small intestine of a dead badger, designated strain M577-94T. Using phenotypic and phylogenetic analyses, they identified this organism as a new genus and species. The bacterium is a facultatively anaerobic, catalase-negative, Gram-positive rod that resembles Carnobacterium in fatty acid composition but differs significantly in cell wall structure. Comparative 16S rRNA gene sequencing revealed it represents a distinct phylogenetic lineage closely related to but separate from Carnobacterium and Desemzia genera. A key distinguishing feature is its unique cell wall murein type based on L-lysine (L-Lys–L-Thr–Gly), unlike Carnobacterium species which contain meso-diaminopimelic acid. The organism produces acid from glucose, glycerol, ribose, and trehalose, and displays specific enzyme activities including arginine dihydrolase and β-glucosidase. Based on both molecular and chemotaxonomic evidence, the authors propose classifying this bacterium as Isobaculum melis gen. nov., sp. nov., with type strain CCUG 37660T (DSM 13760T). The organism's natural habitat remains unknown beyond its isolation from a badger.
Key findings
- Isobaculum melis is a new genus and species of Gram-positive rod-shaped bacteria isolated from badger intestine, phylogenetically distinct from related Carnobacterium and Desemzia genera
- The organism possesses a unique L-lysine-based cell wall murein (L-Lys–L-Thr–Gly type), differing from Carnobacterium species which have meso-diaminopimelic acid walls
- 16S rRNA gene sequencing shows 94-95% similarity to Carnobacterium and 94.5% to Desemzia incerta, but bootstrap analysis confirms it forms a separate phylogenetic lineage
- The bacterium is facultatively anaerobic, catalase-negative, and produces acid from glucose, glycerol, ribose, and trehalose but not from common substrates like lactose and maltose
- DNA G+C content is 39 mol% with characteristic enzyme profiles that distinguish it from all known Carnobacterium species and other related taxa
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Abstract
Phenotypic and phylogenetic studies were performed on a hitherto undescribed facultatively anaerobic, catalase-negative, Gram-positive rod-shaped organism, strain M577-94(T), isolated from the small intestine of a dead badger. It resembled carnobacteria in terms of its long-chain cellular fatty acid composition, but differed markedly from the latter in possessing a cell-wall murein based on L-lysine (type L-Lys--L-Thr--Gly). Comparative 16S rRNA gene sequencing showed that the unknown bacterium represents a new line closely related to, albeit distinct from, the genera Carnobacterium and Desemzia. On the basis of phylogenetic and phenotypic evidence, it is proposed that strain M577-94(T) be classified as Isobaculum melis gen. nov., sp. nov. The type strain of Isobaculum melis is CCUG 37660(T) (=DSM 13760(T)).