Summary auto-generated
This study presents evidence for reclassifying the sulfate-reducing bacterium Desulfobacterium macestii as Desulfomicrobium macestii based on phylogenetic, chemotaxonomic, and metabolic analyses. The organism, originally isolated from a sulfide spring at Matsesta, Russia, was initially classified in genus Desulfobacterium but phylogenetic analysis of 16S rRNA sequences shows it clusters with Desulfomicrobium species, sharing 100% sequence similarity with Desulfomicrobium norvegicum. Chemotaxonomic analysis revealed cellular fatty acid composition and menaquinone (MK-6) content characteristic of Desulfomicrobium rather than Desulfobacterium. DNA-DNA hybridization with D. norvegicum yielded 71.7% reassociation, supporting species-level distinction. Metabolically, strain M-9T exhibits chemoautotrophic growth on hydrogen and formate, and can utilize various alcohols and organic acids as electron donors with sulfate reduction. The organism differs from closely related species by its ability to grow chemoautotrophically on H₂ plus CO₂ and its fermentation capacity on pyruvate and fumarate. These combined data demonstrate that Desulfobacterium macestii belongs within genus Desulfomicrobium in the family Desulfovibrionaceae, warranting formal reclassification to Desulfomicrobium macestii comb. nov.
Key findings
- 16S rRNA sequence analysis places Desulfobacterium macestii within the Desulfomicrobium clade with 100% similarity to D. norvegicum rather than in Desulfobacterium
- Chemotaxonomic analysis reveals characteristic Desulfomicrobium features: branched-chain fatty acids (particularly iso C17:1ω10c) and MK-6 menaquinone absent in Desulfobacterium species
- DNA-DNA hybridization with D. norvegicum yields 71.7% reassociation, supporting close relationship but distinct species status
- Metabolic capabilities distinguish the strain by chemoautotrophic growth on H₂/CO₂ and fermentative growth on pyruvate and fumarate without sulfate
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Abstract
Phylogenetic, chemotaxonomic and metabolic data obtained for Desulfobacterium macestii indicate that this species is not a member of the genus Desulfobacterium, but of the genus Desulfomicrobium. Phylogenetically, it is closely related to Desulfomicrobium baculatum and Desulfomicrobium norvegicum, but it can be differentiated from these species by its metabolic properties. It is therefore proposed to reclassify Desulfobacterium macestii as Desulfomicrobium macestii comb. nov.