POWRE: Methane Oxidizer Biofilms in Landfill Cover Soil: A Study of Film Formation and Community Architecture

University Of North Carolina At Charlotte, Charlotte NC

Investigators

Abstract

0074970 Hilger This research will examine microbial methane oxidizers in the context of their growth in a soil biofilm. Methane oxidizers exposed to high methane concentrations in landfills can produce copious slime secretions, and it is hypothesized that these viscous exopolysaccharides (EPS) may limit diffusion of gases to cells embedded in the biofilm and thereby control methane oxidation rates. The experimental objective of this project is to define the time dependent growth and spatial orientation of methane oxidizers in a biofilm typical of the vadose zone of landfill cover soils. Biofilms enriched in methane oxidizers will be developed on strips of membrane filter paper buried in or placed on top of landfill cover soil and exposed to synthetic landfill gas in a laboratory simulation. Oligonucleotide flourescent dye-tagged probes will be used to investigate methanotroph species distribution in the film and the spatial patterns of the methanotrophs relative to the film secretions. The biofilm structure will be preserved using cryoembedding techniques and observed after cryosectioning using flourescence microscopy-based image analysis. The results of the project will be used to evaluate whether EPS secretions are a significant and heretofore unrecognized influence on methane oxidation capacity in landfill cover soil. If so, the findings could have implications for global methane and climate change models, for the design and management of landfill covers to mitigate methane emissions, and for volatile organic compound emission, adsorption and cometabolism. The techniques and findings may also be applicable to studies of other vadose zone methane oxidizer environments, such as intermittently drained wetlands, bioremediation sites, biofilters, natural gas recovery and leaks through soil and coal mine operations. ***