The effects of glucose concentration on the growth rates of wild type and PDC1 mutant Saccharomyces cerevisiae

Abstract

The PDC1 gene in Saccharomyces cerevisiae accounts for a portion of pyruvate decarboxylase enzyme activity during fermentation (Flikweert et al.1996). In our experiment we wanted to determine whether the presence of a mutation in the PDC1 gene influences the effects of increased glucose concentration on the growth rate of S. cerevisiae. To do this, we incubated wild-type and mutant strains of S. cerevisiae for 24 hours in a 30°C water bath in two different growth media: control (standard, 1X glucose YPD medium) and treatment (2X glucose YPD medium). Then we calculated the growth rates of each cell type in each growth culture using the cell counts taken at scheduled time intervals. We used the two-factor ANOVA to test the statistical significance our results. We found that the growth rate of the wild type was greater in both treatments with an average growth rate of 9.5 x 10^-3 cells/min compared to 4.9 x 10^-3 cells/min of the mutant (p-value=9.2 x 10^-7). There was no statistically significant difference in the growth rates of S. cerevisiae in different glucose concentrations (p-value=0.771548). Further, we did not see any statistically significant interaction between effects of the mutation and the increased glucose concentration (p-value=0.69927). The PDC1 mutation decreased the growth rate of S. cerevisiae; however, increasing glucose concentration of standard YPD medium did not affect the growth rate of wild type and mutant strains of S. cerevisiae.