Lignocellulosic biomass for second-generation biorefineries feedstock can be sustainably obtained from agricultural, industrial or municipal solid wastes, resulting in low environmental impact. However, the main barrier to a more widespread application results from the high cost and difficulty of obtaining fermentable sugars by hydrolysis. Traditionally, saccharification and fermentation are maintained as two separate steps. In order to reduce the cost of biorenewables production from lignocellulose, it is desirable to merge these processes into a single step. A promising approach towards the development of this strategy is the display of a cellulosome and a xylanosome on the surface of Saccharomyces cerevisiae to break down biomass into sugars for growth and product formation. To adapt the enzymatic composition to the substrate available (i.e. hemicellulose or cellulose), we have developed an extracellular sensor that triggers the secretion of cellulases upon detection of residual extracellular glucose derived from lignocellulose pre-treatment. By action of the displayed enzymes, extracellular glucose concentration will then increase, generating a positive feedback loop that will enable efficient cellulose degradation. Moreover, to overcome bottlenecks related to the heterologous nature of the secreted cellulases, we have engineered different steps of the secretory pathway of S. cerevisiae.

Substrate-dependent surface display of a cellulosome by Saccharomyces cerevisiae

251st National Meeting (2016)

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