Production of cellulolytic enzymes from ascomycetes: Comparison of solid state and submerged fermentation

Abstract

Optimizing production of cellulose degrading enzymes is of great interest in order to increase the feasibility of constructing biorefinery facilities for a sustainable supply of energy and chemical products. The ascomycete phylum has a large potential for the production of cellulolytic enzymes. Although numerous enzymatic profiles have already been unraveled, the research has been covering only a limited number of species and genera, thus leaving many ascomycetes to be analyzed. Such analysis requires choosing appropriate media and cultivation methods that ensure enzyme profiles with high specificities and activities. However, the choice of media, cultivation methods and enzyme assays highly affect the enzyme activity profile observed. This review provides an overview of enzymatic profiles for several ascomycetes covering phylogenetically distinct genera and species. The profiles of cellulose degrading enzymes are correlated to the use of submerged culturing and solid state culturing. Even though submerged fermentation (SmF) is the most common method for commercial enzyme production, the use of solid state fermentation (SSF) is praised as a promising way of producing higher enzyme titers compared to SmF. Current comparisons of enzyme activities obtained from SmF and SSF do not account for all variables thereby complicating comparisons and diminishing credibility of conclusions being made. This review aims at providing guidelines for directly comparing cellulolytic enzyme production in SSF with SmF to advance future research of enzyme production.