Cellulolytic
Many microorganisms produce cellulases which hydrolyse the glucose polymer cellulose, releasing glucose, obtaining thereby a substrate for chemoheterotrophic growth.  Some species secrete these enzymes into the extracellular medium and glucose released from the polymer can also be used as a growth substrate by species that do not make cellulases.  The cellulase producers are therefore of primary importance in the metabolic economy of the reticulo-rumen because they provide the growth substrate for other species that would not otherwise grow here.