(85e) Upgrading Acid Whey to Animal Feed Via Metabolic Engineering of Yarrowia Lipolytica

Every year, the dairy industry generates a significant amount of wastewater including whey. Whey can be divided into two main categories comprising sweet whey and acid whey. While sweet whey, which is mainly generated during cheese manufacturing, can be utilized by the food industry due to its higher protein content and lower acid content than acid whey, the latter remains untapped. Acid whey is a by-product of Greek yogurt production, and it contains abundant sugars and nutrients that could be utilized in bioprocesses. The remarkable rise of Greek yogurt sales, and thus of the amount of acid whey generated, rendered its current disposal methods inefficient by imposing extra costs on the dairy producers and posing manifold environmental threats. Hence, the development of an approach that tackles an environmental problem and produces a stream of higher value-added products at the same time is imperative. Moreover, a process that can be easily fitted into existing production facilities, could also reduce the waste treatment cost of acid whey. The proposed bioprocess involves the utilization of acid whey as a feedstock for Yarrowia lipolytica cells that are to be used as animal feed. The Y. lipolytica strain was engineered for the efficient conversion of all acid whey sugars by introducing an extracellular β-galactosidase and amplifying the galactose pathway. In addition, it was genetically modulated for the accumulation of valuable nutritional compounds such as omega 3 fatty acids. This allows the conversion of an environmentally objectionable waste by-product to a nutritious animal feed that can enhance growth and animal health.