The global methane cycle: recent advances in understanding the microbial processes involved

P>The global budget of atmospheric CH(4), which is on the order of 500-600 Tg CH(4) per year, is mainly the result of environmental microbial processes, such as archaeal methanogenesis in wetlands, rice fields, ruminant and termite digestive systems and of microbial methane oxidation under anoxic and oxic conditions. This review highlights recent progress in the research of anaerobic CH(4) oxidation, of CH(4) production in the plant rhizosphere, of CH(4) serving as substrate for the aquatic trophic food chain and the discovery of novel aerobic methanotrophs. It also emphasizes progress and deficiencies in our knowledge of microbial utilization of low atmospheric CH(4) concentrations in soil, CH(4) production in the plant canopy, intestinal methanogenesis and CH(4) production in pelagic water.