Sensitivity of methanotrophic community structure, abundance, and gene expression to CH4 and O2 in simulated landfill biocover soil

Pressure on mitigating CH4 emission in landfill requires better understanding of methanotrophs in landfill biocovers. Most previous studies focused on CH4 as the sole substrate. This study aims to understand the sensitivity of methanotrophs to both substrates CH4 and O-2 concentrations in landfill biocovers. The estimated CH4 oxidation rates (4.66-98.7 x 10(-16) mol cell(-1) h(-1)) were evidently higher than the previous reports, suggesting that activity of methanotrophs was enhanced with both the increasing of O-2 and CH4 concentrations. Denaturing gradient gel electrophoresis based on the amplification of pmoA genes suggested that methanotrophs were more sensitive to CH4 than O-2. Quantification of methanotrophs using pmoA- and mmoX-targeted real-time polymerase chain reaction showed that Mbac and Mcoc as well as Mcys groups were significantly dominant. Mbac group with pmoA gene transcription was dominant. Results indicate that CH4 mitigation would have higher potential by increasing O-2 at appropriate CH4 concentrations. (C) 2013 Elsevier Ltd. All rights reserved.