第七届青年地学论坛

Lakes are freshwater ecosystems, which are characterized by dynamic turnover of methane (CH₄), an important greenhouse gas, serving both as a major source and a major sink. Aerobic CH₄-oxidizing bacteria (methanotrophs) are a key microbial group that oxidizes CH₄ preventing its release into the atmosphere, thereby acting as a natural filter. In natural communities, recent findings suggest that CH₄ consumption occurs as part of a consortium of methanotrophic and non-methanotrophic bacteria, involving the methanotrophs feeding the non-methanotrophs.

In this study, we used artificial communities of methanotrophs and non-methanotrophs in a microcosm model system to decipher mechanisms of community dynamics in lake sediments. We then applied a transcriptomics approach to compare transcriptomes of the individual organisms in artificial communities and in pure cultures.

The results showed that methanol is the dominant carbon and energy source the methanotroph provides to support growth of the non-methanotrophs. We further observed a gene expression shift of the dominant methanol dehydrogenase (MDH) from the lanthanide-dependent MDH (XoxF)-type, to the calcium-dependent MDH (MxaF)-type, in the presence of the non-methanotroph.

These results suggest a cross-feeding mechanism in which the non-methanotrophic partner induces a change in expression of methanotroph MDHs, resulting in methanol transfer to the non-methanotroph. This partner-induced change in gene expression that benefits the partner is a paradigm shift for microbial interactions that may have important implications for understanding interactions of the microbiomes in the environment.
 

Metabolic transformation,Greenhouse gas,Microbiome,Synthetic Ecology,Eco-physiology