Sporomusa aerivorans sp. nov., an oxygen-reducing homoacetogenic bacterium from the gut of a soil-feeding termite

• DOI: 10.1099/ijs.0.02534-0
• Publication Date: 2003-09-16T17:32:36Z
• Authors: Hamadi I. Boga; Wolfgang Ludwig; Andreas Brune
• Keywords: Mesophile

Previously undescribed, homoacetogenic bacteria were isolated from gut homogenates of the soil-feeding termite Thoracotermes macrothorax. The isolates slightly curved, banana-shaped rods (0·6–0·7×1·3–7·0 μm) and motile by one or more lateral flagella. In older cultures, cells formed club-like sporangia that developed into terminal, heat-resistant endospores. Cells stained Gram-positive but Gram-negative in KOH test. mesophilic grew homoacetogenically on H2/CO2 l-lactate. Strain TmAO3T, which was characterized further, also pyruvate, citrate, l-alanine, d-mannitol, ethanol, formate methanol. Succinate decarboxylated to propionate; fumarate, l-malate oxaloacetate fermented propionate acetate. Hexoses not used as substrates. Resting had a large capacity for hydrogen-dependent oxygen reduction [826 nmol min−1 (mg protein)−1], enabled them initiate growth non-reduced basal medium originally contained up 1·5 kPa headspace, although commenced only after been rendered anoxic. Redox difference spectra cell extracts indicated presence membrane-bound b-type cytochrome(s). Comparative 16S rRNA gene sequence analysis revealed strain TmAO3T belongs subgroup phylum is low DNA G+C content wall. It related most closely representatives genus Sporomusa. Based morphological physiological properties similarity 94–97 % other Sporomusa species, are assigned aerivorans sp. nov. (type strain, TmAO3T=DSM 13326T=ATCC BAA-625T).