Protein production: Quality control and secretion stress responses in Trichoderma reesei

Filamentous fungi are commonly used as production hosts in biotechnological industry. This is due to their natural capability to secrete large amounts of protein and metabolites to extracellular culture media. The majority of current commercial protein-based products are based on hydrolytic enzymes or engineered enzyme mixes of fungal origin. However, there is expanding need for new building blocks for chemical and medical industry. Despite the decade-lasting research efforts, the efficient production of heterologous protein targets in Trichoderma reesei has remained challenging. Rapid development of postgenome era tools opens avenues for better understanding of underlying metabolic processes and is a key for clearing the bottlenecks hindering the recombinant protein production in T. reesei. Particularly, better understanding of protein secretion pathway stress responses and quality control is needed to overcome these issues and will be summarized in this chapter.