Cellulases and beyond: the first 70 years of the enzyme producer Trichoderma reesei

Abstract

More than 70 years ago, the filamentous ascomycete Trichoderma reesei was isolated on the Solomon Islands due to its ability to degrade and thrive on cellulose containing fabrics. This trait that relies on its secreted cellulases is nowadays exploited by several industries. Most prominently in biorefineries which use T. reesei enzymes to saccharify lignocellulose from renewable plant biomass in order to produce biobased fuels and chemicals. In this review we summarize important milestones of the development of T. reesei as the leading production host for biorefinery enzymes, and discuss emerging trends in strain engineering. Trichoderma reesei has very recently also been proposed as a consolidated bioprocessing organism capable of direct conversion of biopolymeric substrates to desired products. We therefore cover this topic by reviewing novel approaches in metabolic engineering of T. reesei.

Keywords: Biorefinery; Cellulase; Consolidated bioprocessing; Gene expression; Lignocellulose; Recombinant protein production; Trichoderma reesei.

Fig. 1

a Installed and planned cellulosic ethanol production as of April 2015 in million liter per year (MMLY). Capacity data were compiled from different specialist publications on cellulosic biofuels and press releases of involved consortia and companies. b Number of different technical enzyme preparations produced by individual species. c Number of a given type of enzyme produced by T. reesei (darker color) or other fungi (lighter color). In both cases (B + C) data were retrieved from the list of technical enzymes (2014 version) with kind permission from the Association of Manufacturers and Formulators of enzyme products (http://www.amfep.org). d Number of research papers per year for different fungi retrieved by a Scopus search with the species name as the entry. Results were averaged over 3 year intervals to reduce the effect of random fluctuation. When a second name for the species exists, control searches with both names were performed and the numbers compiled

Fig. 2

Radar chart showing the potential of different fungal and bacterial organisms as CBP organisms. Data were compiled from different reviews and original publications [, –159]. The five biomass sugars are the hexoses glucose, mannose and galactose as well as the pentoses xylose and arabinose