The evolution of different feeding guilds in termites is paralleled by differences in the activity of their gut microbiota. In wood-feeding termites, carbon dioxide-reducing acetogenic bacteria were found to generally outprocess carbon dioxide-reducing methanogenic bacteria for reductant (presumably hydrogen) generated during microbial fermentation in the hindgut. By contrast, acetogenesis from hydrogen and carbon dioxide was of little significance in fungus-growing and soil-feeding termites, which evolved more methane than their wood- and grass-feeding counterparts. Given the large biomass of termites on the earth and especially in the tropics, these findings should help refine global estimates of carbon dioxide reduction in anoxic habitats and the contribution of termite emissions to atmospheric methane concentrations.

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A novel, curved (03i40-50 µm), Gram-negative, non-sporulating, mesophilic bacterium, designated strain ILE-3 T (T l type strain), was isolated from an anaerobic lagoon in a dairy wastewater treatment plant. Optimal growth occurred at 37 SC and pH 74 on a medium containing serine as an energy source and yeast extract.