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P-74. Engineering a biosensor to detect a secreted yeast protease in beer

Presenter: Matthew J. Farber, University of the Sciences, Philadelphia, PA

Proteases are responsible for the cleavage and breakdown of other proteins. Previous studies have demonstrated that the yeast protease, proteinase A (PrA), also called saccharopepsin, is secreted in beer during fermentation. This protease hypothetically degrades foam-promoting proteins, thus decreasing head retention of the beer. Because the concentration of secreted PrA during fermentation has been correlated with yeast viability and proper nutrition, the precise measurement of PrA activity is important for quality control. Previous assays to measure PrA activity have demonstrated non-specificity, low sensitivity, and high cost. Therefore, we have developed a novel, genetically encoded PrA sensor using engineered antibodies that fluoresce after cleavage by PrA. Using less than a drop of beer as the source of PrA, we can measure PrA activity over time. Thus far, we have demonstrated that mechanical disruption of yeast and prolonged storage of yeast increases the activity of PrA. In the future, we hope to use our PrA sensor to measure PrA activity induced by variables such as different yeast strains, improper handling of yeast, and prolonged back slopping. In addition, our platform will allow us to develop sensors for additional yeast proteases that might be relevant to the brewing industry.

Matthew Farber received a B.S. degree in biology from Seton Hall University (South Orange, NJ) and a Ph.D. degree in molecular and cellular biology from the University of Pittsburgh (Pittsburgh, PA). He is currently a postdoctoral fellow under Peter Berget at the University of the Sciences (Philadelphia, PA), specializing in cell biology and protein purification. Specifically, he engineers and produces biosensors capable of measuring the activity of proteases. His interest in brewing led him to apply these sensors to yeast targets relevant to the brewing industry. In addition to research, Matt teaches a graduate course in biotechnology and is currently developing the curriculum for an undergraduate course on the molecular biology of brewing.