Investigation of cell density of BY4741A wild-type and YLR044C mutant strain Saccharomyces cerevisiae in response to varying dextrose conditions

Authors

  • Christie W. Chan
  • Kathleen L. Cruz
  • Harleen Kalra
  • Bonnie Tam
  • Chenxi Yang

Abstract

We compared the effect of varying dextrose concentrations on BY4741A wild-type and YLR044C mutant Saccharomyces cerevisiae cell densities at late log phase. We had two null hypotheses: 1) The wild-type strain of S. cerevisiae will have the same or lower cell density than the PDC1 mutant strain of S. cerevisiae at each dextrose concentration at 29oC at late log phase and 2) At higher dextrose concentration treatment levels, the difference between the wild-type and mutant S. cerevisiae cell density at late log phase will be the same or decrease, in the sense that the difference will be smaller. We tested three dextrose conditions (25.34g/L, 46.66g/L and 89.34g/L) for each of wild-type and mutant S. cerevisiae, with three replicates for each treatment level under the near-optimal temperature condition of 29°C. We took absorbance measurements and converted to cell density by constructing a standard curve through haemocytometer readings of cell density. From our analysis, we reject our first null hypothesis since we observed that the wild-type strain had a significantly higher cell density at late log phase, defined as hour 24 in this experiment, than the PDC1 mutant at 25.34g/L and 46.66g/L dextrose concentrations. Though we did not find a significantly higher cell density at the 89.34g/L dextrose concentration level for wild-type, the wild-type cell density was still higher than mutant. These results are likely occurring because the mutant strain has decreased fermentative growth, which may affect its growth and reproduction. We failed to reject our second null hypothesis since we found that the difference between wild-type and mutant cell density at 89.34g/L was smaller than both the differences in cell density at 25.34g/L and 46.66g/L dextrose medium. Reasons for these results are discussed.

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Published

2014-02-20

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Articles