Natural processes of recycling carbon from plant cell walls are slow but very efficient, generally involving microbial communities and their secreted enzymes. Efficient combinations of microbial communities and enzymes act in a sequential and synergistic manner to degrade plant cell walls. Recent understanding of plant cell wall ultra-structure, as well as the carbon metabolism, ATP production, and ecology of participating microbial communities, and the biochemical properties of their cellulolytic enzymes have led to new perspectives on saccharification of biomass. Microbial communities are dynamic functions of the chemical and structural compositions of plant cell wall components. The primitive 'multicellularity' exhibited by certain cellulolytic microorganisms may play a role in facilitating cell-cell communication and cell-plant cell wall-substrate interaction.