Summary auto-generated
This study describes the characterization and naming of five anaerobic bacterial strains isolated from human oral infections—four from advanced periodontitis and one from a dentoalveolar abscess. These strains, initially classified as Eubacterium species, were subjected to comprehensive phenotypic and genetic analysis. Phylogenetic analysis using 16S rRNA gene sequencing revealed they constituted a novel bacterial lineage in the low G+C Gram-positive bacterial division, most closely related to Erysipelothrix rhusiopathiae and Holdemania filiformis but sufficiently distinct to warrant a new genus and species designation. The authors propose the new genus Bulleidia and species Bulleidia extructa. The organism is an obligate anaerobe, non-motile, non-spore-forming Gram-positive bacillus with poor growth in standard broth media that improves with added fermentable carbohydrates (glucose, maltose, fructose) and Tween 80. Key metabolic features include fermentation of glucose and maltose producing acetate, lactate, and trace succinate, and hydrolysis of arginine. The DNA G+C content is 38 mol%. The type strain is DSM 13220T, and the organism is distinguished from related species by its ability to grow in bile and sensitivity to metronidazole.
Key findings
- A novel bacterial genus and species, Bulleidia extructa, was identified and formally described from five oral cavity isolates obtained from periodontal and dental infections.
- Phylogenetic analysis of 16S rRNA gene sequences placed B. extructa in the low G+C Gram-positive bacterial division, with <90% sequence similarity to its nearest relatives Erysipelothrix rhusiopathiae and Holdemania filiformis, justifying its classification as a new genus.
- B. extructa is an obligate anaerobe with distinctive biochemical characteristics including arginine hydrolysis, fermentation of glucose and maltose, and production of acetate and lactate as primary metabolic end products.
- The organism exhibits poor growth in standard media but is enhanced by addition of fermentable carbohydrates and Tween 80, and is bile-sensitive and metronidazole-susceptible.
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Abstract
Five strains of anaerobic non-sporing Gram-positive bacilli isolated from advanced periodontitis (four strains) and a dentoalveolar abscess (one strain) that did not correspond to existing species were subjected to phenotypic and genetic characterization. Following 16S rDNA sequence analysis, they were found to constitute a novel branch of the low G+C Gram-positive division of the phylogenetic tree related to Erysipelothrix rhusiopathiae and Holdemania filiformis. A new genus Bulleidia, and the species Bulleidia extructa, are proposed. Growth of B. extructa in broth media was poor but was enhanced by the addition of fructose, glucose or maltose together with Tween 80. Glucose and maltose were fermented and arginine was hydrolysed. Acetate, lactate and trace amounts of succinate were the end products of glucose fermentation. The G+C content of the DNA of the type strain is 38 mol%. The type strain of Bulleidia extructa is DSM 13220(T).