Summary auto-generated
This paper describes the reclassification of Clostridium hydroxybenzoicum into a new genus Sedimentibacter and the discovery of a new species. Strain ZF2T, a motile, rod-shaped, anaerobic bacterium isolated from River Saale sediment in Germany, shares 94.4% 16S rRNA gene sequence similarity with C. hydroxybenzoicum strain JW/Z-1T. However, these strains differ significantly in their biochemical properties. Unlike JW/Z-1T, strain ZF2T lacks the ability to carboxylate phenol or decarboxylate 4-hydroxybenzoate—key metabolic traits of the original species. Both strains are Gram-positive, endospore-forming bacteria requiring yeast extract for growth and fermenting amino acids and pyruvate. Phylogenetic analysis using 16S rDNA reveals they form a distinct cluster peripherally associated with clostridial clusters. Based on these phylogenetic and phenotypic differences, the authors establish Sedimentibacter as a new genus with S. hydroxybenzoicus (the reclassified former C. hydroxybenzoicum) as the type species, and describe strain ZF2T as a new species, S. saalensis. Both organisms have DNA G+C contents around 34-35 mol% and share similar peptidoglycan types and fatty acid profiles.
Key findings
- Clostridium hydroxybenzoicum reclassified as Sedimentibacter hydroxybenzoicus gen. nov., comb. nov., establishing a new genus of low-G+C Gram-positive bacteria
- Sedimentibacter saalensis sp. nov. (strain ZF2T) identified as a novel species sharing 94.4% 16S rRNA similarity with S. hydroxybenzoicus but lacking carboxylation/decarboxylation enzymatic activities
- Both Sedimentibacter species are strictly anaerobic, motile rods requiring yeast extract, fermenting pyruvate and amino acids to acetate and butyrate, but not utilizing carbohydrates or purines
- Phylogenetic analysis shows Sedimentibacter forms a distinct lineage peripherally associated with clostridial cluster XIII, branching separately from cluster XII organisms
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Abstract
A. Breitenstein, J. Wiegel, C. Haertig, N. Weiss, J. R. Andreesen and U. Lechner
Institut fur Mikrobiologie, Martin-Luther-Universitat Halle, Kurt-Mothes-Strasse 3, 06099 Halle, Germany
Strain ZF2(T), isolated from freshwater sediment, is a motile, rod-shaped, Gram-positive, endospore-forming, amino acid- and pyruvate-utilizing, anaerobic bacterium. It requires yeast extract for growth. Carbohydrates are not utilized. The optimal temperature and pH for growth are 37 degrees C and 6.8--7.3, respectively. The G+C content of the DNA is 34.0 mol%. A 16S rDNA sequence analysis of strain ZF2(T) revealed that the highest similarity (94.4%) was shared with Clostridium hydroxybenzoicum JW/Z-1(T). Strain ZF2(T), however, was not able to carboxylate phenol or to decarboxylate 4-hydroxybenzoate, which are characteristic properties of strain JW/Z-1(T). The degree of 16S rDNA relatedness, together with the physiological and chemotaxonomic properties, suggest that strain ZF2(T) represents a novel species that is clearly distinct from Clostridium hydroxybenzoicum JW/Z-1(T). In a phylogenetic dendrogram, both strains form a separate cluster that is peripherally associated with the Peptostreptococcus group (cluster XIII) of the clostridia and the lineage of Helcococcus kunzii. Strains ZF2(T) and JW/Z-1(T) show a somewhat deeper branching from the cluster XII clostridia Clostridium purinolyticum and Clostridium acidiurici. The latter strains possessed the closest 16S rDNA similarity (between 88.4 and 90.7%), but were clearly separated by phenotypic markers. Therefore, a new genus, Sedimentibacter gen. nov., is described, comprising Sedimentibacter hydroxybenzoicus gen. nov., comb. nov., as the type species of the genus, with JW/Z-1(T) (=ATCC 51151(T)=DSM 7310(T)) as the type strain, and the novel species Sedimentibacter saalensis sp. nov., with strain ZF2(T) (=DSM 13558(T)=ATCC BAA-283(T)) as the type strain.