MICROBIAL OXIDATION OF CH4 AT HIGH PARTIAL PRESSURES IN AN ORGANIC LANDFILL COVER SOIL UNDER DIFFERENT MOISTURE REGIMES

The uptake and utilization of CH4 at high concentrations (5-18% vol.) and different soil moistures were followed for samples From a landfill cover soil with a high organic matter content. Measurements of the ut ilization of CH4 and O-2, and production of CO2 indicated that the act ivity of methanotrophic organisms accounted for most of the O-2 respir ation. At water saturation, CH4 oxidation rates decreased with time, p robably because NH4+ accumulated. Denitrification rates, estimated bas ed on both N-2 and N2O production, were positively related to soil moi sture and only slightly influenced by the extent of CH4 oxidation. Tot al phospholipid fatty acid concentrations increased, and concentration s of phospholipid fatty acids, typical for obligate methanotrophic bac teria (e.g, 16:1 omega 8 and 18:1 omega 8), increased in the CH4-amend ed samples, indicating growth of both type I and type II methanotrophs , (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.