Abstract
Laboratory experiments were conducted to study the population size, diversity and methane oxidation potential of methanotrophs in tropical rice agroecosystem under the influence of N-fertilizer. Results indicate that the diversity of methane oxidizing bacteria (MOB) is altered in fertilizer treated soils compared to untreated control. Nevertheless, Type I MOB still dominated in the fertilized soils whereas the diversity of Type II methanotrophs decreases. Control soils have higher MOB population and CH(4) oxidation capacity than fertilized soils. Rhizospheric soil is more populated than non-rhizospheric soil in both unfertilized and fertilized conditions. Variation in K(m) and V(max) of methane oxidation in soils appears to be due to variation in methanotrophic community. Experimental results indicate that methanotrophic community differs both quantitatively and qualitatively in unfertilized and fertilized soils.