A Simple Cost Effective Treatment for Declumping Super Yeast

Leo L. Chan, Ashley Wilson, Kelsey McCulley, and Belen Belete-Gilbert

In the early fermentation stages, many types of yeast cells form clusters that can increase the difficulty of both manual cell counting and automated image-based cell counting. In this work, we demonstrate a simple and cost effective method for declumping yeast cells in order to facilitate accurate cell counting and viability measurements. We examined the WLP090 San Diego Super Yeast which is characterized by high clumping during fermentation. A beer sample with Super Yeast was collected from the fermentation tank and treated with a small dose of hydrogen chloride (HCl) for 10-30 seconds. A control sample was treated with the same dose of water for the same duration. Concentrations of both samples were then measured in the Cellometer X2 image cytometer. The yeast concentration as measured by the Cellometer was higher in the sample treated with HCl due
to more accurate yeast identification in the single cell suspension. The accuracy of yeast counting can be easily verified visually by the user after a count. The declumping method also improved the accuracy of measuring
viability with PI using Cellometer X2. By utilizing the acid-based declumping method, clumpy yeast or yeast in the early stages of fermentation can be made into a single cell suspension, which improves the accuracy in cell counting and viability