@article {1564, title = {A field trial of nutrient stimulation of methanotrophs to reduce greenhouse gas emissions from landfill cover soils.}, journal = {J Air Waste Manag Assoc}, volume = {63}, year = {2013}, month = {2013 Mar}, pages = {300-9}, abstract = {

UNLABELLED: Landfills are among the major sources of anthropogenic methane (CH4) estimated to reach 40 x 10(9) kg per year worldwide by 2015 (IPCC, 2007). A 2 1/2-year field experiment was conducted at a closed landfill in western Michigan where methanotrophs, methane-consuming bacteria, were stimulated by nutrient addition to the soil without significantly increasing biogenic nitrous oxide (N2O) production. The effects of the nitrogen amendments (KNO3 and NH4Cl), phenylacetylene (a selective inhibitor of nitrifying bacteria that contribute to N2O production), and a canopy (to reduce direct water infiltration) on the vertical soil gas profiles of CH4, CO2, and O2 were measured in the top meter of the soil. Methane and nitrous oxide fluxes were calculated from the corresponding soil gas concentration gradients with respect to depth and a Millington-Quirk diffusivity coefficient in soil derived empirically from soil porosity, water content, and diffusivity coefficients in air from the literature. Methane flux estimates were as high as 218.4 g m(-2) day(-1) in the fall and 12.8 g/m(-2) day(-1) in the summer. During the spring and summer CH4 fluxes were reduced by more than half by adding KNO3 and NH4Cl into the soil as compared to control plots, while N2O fluxes increased substantially. The concurrent addition of phenylacetylene to the amendment decreased peak N2O production by half and the rate of peak methane oxidation by about one-third. The seasonal average methane and N2O flux data were extrapolated to estimate the reduction of CH4 and N2O fluxes into the atmosphere by nitrogen and inhibitor addition to the cover soils. The results suggest that such additions coupled with soil moisture management may provide a potential strategy to significantly reduce greenhouse gas emissions from landfills.

IMPLICATIONS: The results of a 2 1/2-year study of effects of nutrient stimulation on methane oxidation in landfill cover soils demonstrates that nutrient addition does decrease methane emissions. The work further underscores the control which soil moisture exerts on methane oxidation. Water management is critical to the success of methane oxidation strategies.

}, keywords = {Biodegradation, Environmental, Gases, Greenhouse Effect, Methane, Oxidation-Reduction, Soil, Soil Microbiology, Waste Management}, issn = {1096-2247}, author = {Lizik, William and Im, Jeongdae and Semrau, Jeremy D and Barcelona, Michael J} } @article {1568, title = {Pollutant degradation by a Methylocystis strain SB2 grown on ethanol: bioremediation via facultative methanotrophy.}, journal = {FEMS Microbiol Lett}, volume = {318}, year = {2011}, month = {2011 May}, pages = {137-42}, abstract = {

A facultative methanotroph, Methylocystis strain SB2, was examined for its ability to degrade chlorinated hydrocarbons when grown on methane or ethanol. Strain SB2 grown on methane degraded vinyl chloride (VC), trans-dichloroethylene (t-DCE), trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), and chloroform (CF), but not dichloromethane (DCM). Growth on methane was reduced in the presence of any chlorinated hydrocarbon. Strain SB2 grown on ethanol degraded VC, t-DCE, and TCE, and 1,1,1-TCA, but not DCM or CF. With the exception of 1,1,1-TCA, the growth of strain SB2 on ethanol was not affected by any individual chlorinated hydrocarbon. No degradation of any chlorinated hydrocarbon was observed when acetylene was added to ethanol-grown cultures, indicating that this degradation was due to particulate methane monooxygenase (pMMO) activity. When mixtures of chlorinated alkanes or alkenes were added to cultures growing on methane or ethanol, chlorinated alkene degradation occurred, but chlorinated alkanes were not, and growth was reduced on both methane and ethanol. Collectively, these data indicate that competitive inhibition of pMMO activity limits methanotrophic growth and pollutant degradation. Facultative methanotrophy may thus be useful to extend the utility of methanotrophs for bioremediation as the use of alternative growth substrates allows for pMMO activity to be focused on pollutant degradation.

}, keywords = {Autotrophic Processes, Biodegradation, Environmental, Environmental Pollutants, Ethanol, Hydrocarbons, Chlorinated, Methane, Methylocystaceae}, issn = {1574-6968}, doi = {10.1111/j.1574-6968.2011.02249.x}, author = {Im, Jeongdae and Semrau, Jeremy D} }