A methane‐driven microbial food web in a wetland rice soil

Summary Methane oxidation is a key process controlling methane emission from anoxic habitats into the atmosphere. Methanotrophs, responsible for aerobic methane oxidation, do not only oxidize but also assimilate methane. Once assimilated, methane carbon may be utilized by other organisms. Here we report on a microbial food web in a rice field soil driven by methane. A thin layer of water‐saturated rice field soil was incubated under opposing gradients of oxygen and 13 C‐labelled methane. Bacterial and eukaryotic communities incorporating methane carbon were analysed by RNA‐stable isotope probing (SIP). Terminal restriction fragment length polymorphism (T‐RFLP) and cloning showed that methanotrophs were the most prominent group of bacteria incorporating methane carbon. In addition, a few Myxobacteria ‐related sequences were obtained from the ‘heavy’ rRNA fraction. Denaturing gradient gel electrophoresis (DGGE) targeting 18S rRNA detected various groups of protists in the ‘heavy’ rRNA fraction including naked amoeba ( Lobosea a