The effect of stress due to sodium chloride exposure on the growth of <i>Saccharomyces cerevisiae</i>

Abstract

Throughout its many industrial applications, Saccharomyces cerevisiae is exposed to a variety of sodium chloride (NaCl) concentrations that limit its functionality. The objective of this experiment was to study the effect of increasing stress posed by sodium chloride on the growth rate of wild-type S. cerevisiae. We created three different media containing 0g/L, 30g/L, and 60g/L NaCl for S. cerevisiae growth while incubated at 30ºC. Samples were taken every hour for six hours and cell counts were determined using a haemocytometer. Our results revealed overall increasing growth. However, increasing salt concentrations resulted in slower growth rates with mean final concentrations of 3.14 x 10⁶ cells/mL, 1.05 x 10⁶ cells/mL, and 4.21 x 10⁵ cells/mL in our 0g/L NaCl, 30g/L NaCl and 60g/L NaCl, respectively. A two-way ANOVA test provided three p-values<0.05 that allowed us to support our alternate hypotheses. NaCl dehydrates and disrupts S. cerevisiae cells which in turn rely on coping mechanisms involving ion uptake regulation and carbohydrate production for cell protection. We concluded that increasing NaCl concentration and increasing time, as well as the interaction between these two factors, had an effect on the growth rate of S. cerevisiae. All cultures had increasing cell concentrations as time progressed, but cultures exposed to higher NaCl concentrations experienced reduced growth rates, possibly due to the fact that energy was redirected from reproduction processes to the osmotic stress response.