Development of Cereal-Based Biorefineries for the Production of Biodegradable Plastics and Platform Chemicals

In the Satake Centre for Grain Process Engineering we are developing cereal-based biorefining strategies for the production of biofuels, biodegradable plastics and platform chemicals. Cereal grains are complex biological entities and we target the exploitation of all cereal components providing both value-added end-products and precursors for chemical synthesis. Hydrolysis of natural polymers (e.g. starch, protein) contained in cereals requires supply of a range of hydrolytic enzymes (e.g. amylase, protease), which are produced by fungal bioconversions. On-site production of these enzymes would result in the production of a high amount of fungal biomass. Fungal autolysis can be used to bioconvert this low-cost byproduct into a nutrient-rich supplement (fungal extract) for microbial bioconversions. Mixing fungal extracts with cereal hydrolysates results in nutrient-complete microbial feedstocks. Optimising the exploitation of protein in cereal grains would enable the provision of optimum amounts of free amino acids and peptides to subsequent microbial bioconversions and the extraction of the remaining protein as a value-added co-product with various current (food) and potential (biodegradable plastics) market outlets. The use of amino acids and peptides would enhance productivities (e.g. polyhydroxybutyrate, succinic acid) and, in certain cases, production yields (e.g. polyhydroxybutyrate) improving significantly current fermentation practices that exploit only the starch component in cereal grains. In addition, the exploitation of all cereal components and low-cost by-product streams produced in a cereal-based biorefinery will result in waste minimisation and maximisation of carbon as well as other nutrient utilisation from the original cereal grain. This work will present different feedstock formulation strategies based on the production of wheat hydrolysates and fungal extracts for the microbial production of polyhydroxybutyrate and succinic acid.