The study investigates the role of viruses in modulating microbial methane metabolism (MM) across various habitats. By analyzing 982 publicly available metagenomes, the researchers identified 24 auxiliary metabolic genes (AMGs) that could potentially participate in MM pathways, including seven exclusive to MM. These AMGs were found on 911 viral contigs, which were predicted to infect 14 prokaryotic phyla. The majority of these AMGs were associated with rumen habitats, while fewer were found in environmental habitats. To further explore this, the researchers generated metagenomes from methane-rich sediments in Vrana Lake, Croatia, and found diverse viral communities with most viruses infecting methanogens and methanotrophs. However, none of the AMGs identified in the lake sediments directly participated in MM pathways. The findings suggest that the extent to which viruses modulate host metabolic processes, such as MM, varies depending on the ecological properties of the habitat and is not always predictable by habitat biogeochemical properties. This highlights the need to include viruses in future ecosystem and geochemical models of MM to better understand and mitigate microbially driven methane emissions and climate warming.The study investigates the role of viruses in modulating microbial methane metabolism (MM) across various habitats. By analyzing 982 publicly available metagenomes, the researchers identified 24 auxiliary metabolic genes (AMGs) that could potentially participate in MM pathways, including seven exclusive to MM. These AMGs were found on 911 viral contigs, which were predicted to infect 14 prokaryotic phyla. The majority of these AMGs were associated with rumen habitats, while fewer were found in environmental habitats. To further explore this, the researchers generated metagenomes from methane-rich sediments in Vrana Lake, Croatia, and found diverse viral communities with most viruses infecting methanogens and methanotrophs. However, none of the AMGs identified in the lake sediments directly participated in MM pathways. The findings suggest that the extent to which viruses modulate host metabolic processes, such as MM, varies depending on the ecological properties of the habitat and is not always predictable by habitat biogeochemical properties. This highlights the need to include viruses in future ecosystem and geochemical models of MM to better understand and mitigate microbially driven methane emissions and climate warming.