Anthony J. Wavrin Week 2

Question 1

• Before beginning to change the parameters of the equation, and therefore the chemostat, I became familiar with what the values actually signified. There were two variables that were the dependent variables, cell population and chemostat concentration. The rest of the variables were parameters, such as inflow rate, inflow concentration, nutrient saturation level, and efficiency of uptake by the cells. I then began to manipulate the parameters of the chemostat in an attempt to observe trends. I found that increasing the inflow rate actually quickens population death. However, increasing the concentration of the inflow had the opposite effect. Also, increasing the growth rate resulted in less available nutrients, which is what would be expected. Lastly, I did not find the % saturation having any large effect on the cell population. I have provided a PDF of some manipulated plots.

Question 2

• With the new logistic growth model, I began to manipulate the parameters as I had done earlier. The chemostat responded in relatively the same manner as with the first model. The inflow rate increase yielded the exact same results. However, increasing the concentration of the inflow did not slow the death of the cell population as drastically. Increasing the nutrient saturation level did lead to a more quick death and resulting in an increase in nutrients. Lastly, the new parameter, a, did not have any noticeable affect when modified. I have provided a PDF of some manipulated plots.

• With this model, there are a few adjustments that could be made. The model does not take into account that there will be a concentration gradient from the inflow to the outflow. Also, it does not take into account waste and how harmful it can be. As stated in the question, yeast, like any organism, releases waste (alcohol). This waste can be toxic in high concentrations. Therefore, if there is a lack of clearing of the yeast’s waste, it can lead directly to yeast dying, which currently isn’t accounted for.