Elucidating the xylose metabolism pathway in thraustochytrids for the conversion of hemicellulosic waste into omega-3 fatty acids and biofuel.

Canada's vast forests and developed forestry industry place it in a unique position to take advantage of woody biomass from sawmill residue as a feedstock for the production of value-added products. In a similar process to common alcoholic fermentation, the use of specialized microorganisms offers the opportunity to convert pulp into a wide range of consumer and industrial chemicals. However, the xylose or "wood" sugar that makes up a large fraction of this biomass is not readily digestible by most common microorganisms. One group of microorganisms that are capable of naturally utilizing xylose is the thraustochytrids -- marine protists that feed on dead plant matter. Furthermore, this group of microorganisms are also capable of producing large quantities of nutritionally important lipids, making them an ideal target for industrial exploitation. Mara Renewables Corporation is an Atlantic Canadian producer of algal-based bio-products that is currently using thraustochytrids in their commercial production of omega-3 fatty acids. However, there are significant challenges to using woody biomass as a primary feedstock at commercial scales -- natural xylose consumption is relatively slow and xylose is only consumed once other sugars have been exhausted. Through the proposed project, Mara Renewables seeks to better understand xylose metabolism in thraustochytrids to engineer a cell line capable of growing on xylose at industrially relevant scales. The proposed study will make use of nuclear magnetic resonance to understand how the cell breaks down xylose and what byproducts are produced. This information will then be combined with genetic data to develop a mathematical model capable of predicting the effect of specific genetic engineering strategies. The goal is to develop a genetic engineering strategy that will result in rapid cell growth and high lipid yield. The result will be to enable the exploitation of common waste stream from industrial processes such as pulp and paper manufacturing to produce valuable consumer goods in a sustainable and cost-effective manner.