Presentation on theme: "Killer Yeast vs. Sensitive Yeast Data from experiments in a chemostat undertaken by Nick McClure, a former PhD student in the department Killer yeasts."— Presentation transcript:
Killer Yeast vs. Sensitive Yeast Data from experiments in a chemostat undertaken by Nick McClure, a former PhD student in the department Killer yeasts are yeasts that secrete exotoxins that kill susceptible (sensitive) yeast cells. The yeast studied here was a budding yeast used in baking known as Saccharomyces cerevisiae. K S Interestingly, these killer yeast cells carry a gene that confers immunity against the exotoxins they produce. When grown in isolation, killer yeast cells may have lower reproductive rates than susceptible yeast cells because resources normally invested in growth are shunned in favor of exotoxin production. When grown in competition, killer yeast cells are likely to outcompete susceptible yeasts due to the exotoxins.
The Data Sensitive (S A,S B ) and killer (K A,K B ) yeast strains were grown in duplicate, both in isolation. Yeast cell density was measured as optical density (OD) taken when population growth stabilized at different flow rates (measured as vessel volumes per hour (VVH)). SASBKAKBSASBKAKB
Statistical Components Characterization of uncertainty in yeast replicates Is the change in optimal density over time the same for killer yeast as susceptible yeast? If not, by how much do they differ? Dynamical Components Model for yeast Growth in a chemostat as a function of time based on the amount of glucose available for the yeast. For G = glucose concentration, Y = yeast conc.: dG/dt = ? dY/dt = Competition growth model for killer and susceptible yeast as a function of time with glucose interaction No data available for competition model, but can use statistical model to estimate dynamical model parameters