The saccharification step: Trichoderma reesei cellulase hyper producer strains

Abstract

One of the major applications of cellulases is to produce fermentable sugars from lignocellulosic biomass for biofuels production. The filamentous fungus Trichoderma reesei is known to be hyper producer of cellulases and hemicellulases and it is widely used for commercial scale production of these enzymes using novel fermentation techniques. Some of the T. reesei industrial strains produce over 100 g/l of cellulases. However, there are still technical and economic constraints to the development of cheap commercial cellulase production process. Here, we bring together and discuss the results on T. reesei as cellulase producer, the different kinds of enzymes it expresses, recent genomic, genetic, and metabolic engineering approaches that have helped to improve the biomass degrading enzyme mixture and the strategies adopted to reduce the cost of enzymes during fermentation process. Current efforts and some future perspectives for reducing the cost of enzymes by using cheaper substrates, recycling enzyme during the hydrolysis and fermentation process, and on-site enzyme production in the biorefinery facility are also discussed.