The anaerobic foodweb can be viewed as a large network of trophic interactions between hundreds of species of Bacteria and Archaea. This ensemble converts a complex starting substrate to methane and CO2 via a range of intermediate metabolites. One could imagine various solutions to the anaerobic foodweb that are functionally redundant but differ in community structure and performance of ecosystem function (i.e. biogas yield). For commercial engineered systems like full-scale anaerobic digesters, however, the interaction network seems to be constructed around a set of core microorganisms systematically present in a range of samples, as reported in the literature. This points towards the importance of characteristic members of the foodweb that determine the performance of an anaerobic digester. However, less attention has been paid to keystone species or keystone networks that may have a disproportionate role in the anaerobic digestion despite their low abundance.