Molecular Switch in Fungi Opens New Opportunities for Biofuel Production

In Vienna, scientists have characterized a mutation in a strain of biomass-degrading fungus that constantly ‘switches on' the production of the desired degrading enzymes even without the inducing factor.

Production of biofuels from lignocellulose materials such as woods and grasses requires the enzymatic breakdown of the long cellulose and xylan components of the biomass into simple fermentable sugars. Industries typically use certain strains of fungi to produce the biomass-degrading cellulase and xylanase enzymes, but only in the presence of a chemical inducer. The high cost of chemical induction somehow pushes up the cost of biofuel manufacturing.

This prompted a research at the Vienna University of Technology seeking to understand the genetic mechanism of regulating the production of cellulase and xylanase in fungus Trichoderma reesei. In one of the T. reesei strains, the researchers found a random mutation that affected the molecular switch linked with the induction mechanism, a gene called xylanase regulator 1 or xyr1. The mutation stopped the chemical switch from functioning so that even without or regardless of an inducer, the fungus always produces the desired enzymes.

Detailed genetic analysis has identified the specific DNA sequence required for this behavior. The findings, published in the journal Biotechnology for Biofuels, open the possibility toward a more directed approach of inducing the same mutation in other fungal strains. Genetic manipulations are now being tested toward further strain engineering to produce even more productive fungi. This would make the production of fuel from lignocellulose more economically attractive.