A highly active extracellular cellulase from the anaerobic rumen fungus<i>Neocallimastix frontalis</i>

An extracellular cellulase which was highly active in solubilizing the highly hydrogen bond-ordered cellulose in cotton fibre was found in a culture filtrate of the anaerobic fungus, Neocallimastix frontalis, isolated from the rumen of a sheep. The cellulase was several-fold more active in solubilizing cotton fibre per unit of endo-1,4-β-glucanase than the cellulase of the aerobic fungus Trichoderma reesei mutant strain C-30, which is one of the most active cellulases isolated so far.