Production of Industrial Enzymes in Trichoderma reesei

The mesophilic filamentous fungus Trichoderma reesei (teleomorph Hypocrea jecorina) has become a major cell factory in the enzyme industry, and the benchmark organism for production of cellulases, especially for biomass conversion. The strain was originally isolated during the second World War from US Army tent canvas in the Solomon Islands and initially identified as Trichoderma viride. The isolate was designated QM6a since the strain was part of a collection at the US Army QuarterMaster Research and Development Centre at Natick, Massachusetts (Mandels and Reese 1957). Later QM6a was shown to be distinct from the already known T. viride and was renamed T. reesei in honour of the Natick laboratory researcher Elwyn T. Reese. For a long time, T. reesei was used only as a model organism for cellulose degradation studies. The worldwide demand for alternative fuel sources in the mid1970s meant that the potential of T. reesei to produce cellulases to hydrolyse cellulose-rich biomass into fermentable sugars was of great interest, as it is again today. In general, many filamentous fungi have the potential to produce high amounts of extracellular proteins. Yet, the production level of any protein of interest in naturally occurring strains is usually too low for commercial exploitation, rendering substantial strain improvement programs essential (Punt et al. 2002). Therefore, using ran-