Diversity and Dynamics of Methanotrophs within an Experimental Landfill Cover Soil

Abstract

Three experimental biocovers were installed during the summer of 2006 at the St‐Nicéphore landfill in Québec (Canada). The main objectives of the experimental program were to assess the efficiency of these biocovers in reducing CH4 emissions and to monitor the evolution in space and time of the dynamics and diversity of methanotrophic bacteria that may be responsible for CH4 abatement. Dynamics of methanotroph populations derived from most probable number (MPN) counts exhibited different steps (lag, growth, and collapse phases), with mean abundances decreasing somewhat with depth. Methanotroph diversity, as assessed by denaturing gradient gel electrophoresis showed changes over time in the community structure. These changes were dependent on the sampling depth and only Type I methanotrophs belonging essentially to the genus Methylobacter were retrieved from our samples. Given the youthful character of the system under study, together with the reported behavior of this functional group of methanotrophs, it was concluded that Type I methanotrophs forming the community structure might reflect pioneer species with a potentially high growth rate (r‐strategists) that become numerically dominant reducing the evenness of species distribution. These results contribute to the generally limited body of knowledge on methanotroph diversity in landfill cover soils.