Summary auto-generated
Sporomusa silvacetica sp. nov. is a newly described acetogenic bacterium isolated from well-drained forest soil in Germany. The organism is an obligate anaerobe with slightly curved rod morphology, lateral flagella, and the ability to form terminal spores. It grows optimally at 30°C and pH 6.8, with a doubling time of approximately 14 hours on fructose. The bacterium utilizes a diverse range of substrates including sugars, organic acids, alcohols, and aromatic compounds derived from lignin degradation, producing acetate as the primary end product through the acetyl-CoA pathway. Phylogenetic analysis of 16S rRNA gene sequences places it within the genus Sporomusa in the Clostridium subphylum. The organism possesses carbon monoxide dehydrogenase and hydrogenase activities and contains a type b cytochrome in its membrane. With a G+C content of approximately 43 mol%, S. silvacetica represents the first Sporomusa species isolated from terrestrial, well-drained soils, suggesting certain Sporomusa species can adapt to fluctuating anaerobic conditions. The isolation confirms acetogens are present and potentially active in anaerobic microsites within forest soils.
Key findings
- Sporomusa silvacetica is a newly described acetogenic bacterium isolated from forest soil soil capable of producing acetate through the acetyl-CoA pathway using diverse substrates including sugars, organic acids, and lignin-derived aromatics
- The organism is an obligate anaerobe with curved rod morphology and terminal spore formation, growing optimally at 30°C and pH 6.8 with a doubling time of 14 hours on fructose
- Phylogenetic analysis of 16S rDNA places S. silvacetica within the genus Sporomusa with 97.2% sequence similarity to S. paucivorans
- This is the first Sporomusa species isolated from terrestrial well-drained soils, indicating certain Sporomusa species can adapt to environments with fluctuating redox conditions and aeration
- The bacterium possesses carbon monoxide dehydrogenase and hydrogenase activities, uses fumarate and aromatic acrylate groups as electron acceptors, and contains a membrane-bound type b cytochrome
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Abstract
Sporomusa silvacetica sp. nov. DG-1T (= DSMZ 10669T) (T = type strain) was isolated from well-drained, aggregated forest soil (pH 6.0) in east-central Germany. The cells were obligately anaerobic, slightly curved rods and were motile by means of laterally inserted flagella on the concave side of each cell. Typical cells were approximately 3.5 by 0.7 µm. Cells stained weakly gram positive, but thin sections revealed a complex multilayer cell wall. Spores were spherical and distended the sporangia. Growth and substrate utilization occurred with ferulate, vanillate, fructose, betaine, fumarate, 2,3-butanediol, pyruvate, lactate, glycerol, ethanol, methanol, formate, and H2-CO2. With most substrates, acetate was the primary reduced end product and was produced in stoichiometries indicative of an acetyl-coenzyme A pathway-dependent metabolism. Fumarate was dismutated to succinate and acetate. Methoxyl and acrylate groups of various aromatic compounds were O-demethylated and reduced, respectively. Yeast extract was not required for growth. Cells grew optimally at approximately 30°C and pH 6.8; under these conditions and with fructose as the substrate, the doubling time was approximately 14 h. The lowest temperature that supported growth was between 5 and 10°C. The carbon monoxide dehydrogenase and hydrogenase activities were approximately 9 and 102 µmol min-1 mg of protein-1, respectively. A type b cytochrome was detected in the membrane. The G+C content was approximately 43 mol%. Phylogenetic analysis of the 16S ribosomal DNA indicated that DG-1T was most closely related to members of the genus Sporomusa in the Clostridium subphylum of the gram-positive bacteria.