Growth Rate Comparisons between Dextrose and Lactose in Saccharomyces cerevisiae

Abstract

Brewer’s yeast or Saccharomyces cerevisiae, is an ingredient used to make beer or bread. During fermentation, yeast turns sugar into alcohol, which is essential in brewing. Our group wanted to see which sugar, dextrose or lactose, would make the growth of brewer’s yeast the highest. To do this, we made yeast solutions of both dextrose and lactose in separate falcon tubes. After one week, light absorption was measured and recorded to find the growth rate of the yeast. We hypothesized that lactose compared to dextrose, would have a lower growth rate due to dextrose’s simpler structure. After calculating the change in light absorption over time, our results showed that lactose, the disaccharide, had the higher effect on the yeast’s growth rate. These results did not support our hypothesis.