Hydrogen turnover by psychrotrophic homoacetogenic and mesophilic methanogenic bacteria in anoxic paddy soil and lake sediment

Abstract

The effect of temperature on CH4 production, turnover of dissolved H2, and enrichment of H2-utilizing anaerobic bacteria was studied in anoxic paddy soil and sediment of Lake Constance. When anoxic paddy soil was incubated under an atmosphere of H2/CO2, rates of CH4 production increased 25°C, but decreased at temperatures lower than 20°C. Chloroform completely inhibited methano-genesis in anoxic paddy soil and lake sediment, but did not or only partially inhibit the turnover of dissolved H2, especially at low incubation temperatures. Cultures with H2 as energy source resulted in the enrichment of chemolithotrophic homoacetogenic bacteria whenever incubation temperatures were lower than 20°C. Hydrogenotrophic methanogens could only be enriched at 30°C from anoxic paddy soil. A homoacetogen