Human Practices: Gold Requirement

Probiotic as a Prophylactic: Insight from the Department of Environmental Protection

Bacterial Insight from Dr. Shell

We met with WPI’s microbiologist Scarlett Shell with the goals of:

1. Adjusting our protocols for growth curve and lead plate experiments

2. Learning how to analyze our data for these experiments appropriately

Professor Shell suggested that that the first step in our effort to understand how B. subtilis and L. rhamnosus respond to lead exposure should be to focus on testing the bacteria in liquid media through growth curves. We were advised to begin growth curves with a starting OD of 0.01 as opposed to the starting OD of 0.1 which we had been using previously. Beginning growth curves with fewer cells would reduce the shielding effect that occurs that prevents cells in a culture from responding to lead in the way they would normally. Measuring ODs at each hour and plotting them as each culture grew was the method we had previously used to observe culture growth over time. However, Professor Shell advised that we additionally graph our OD data on a log10 scale. This would allow us to visually see when culture growth was negatively affected by lead when we saw no change in the logarithmic growth.

Additionally, Professor Shell suggested that we modify our lead plate streaking protocols in order to make them more quantifiable. Instead of streaking plates with a colony and observing decreased colony size and number qualitatively, it was suggested that we roll liquid cultures with known ODs onto plates with beads. Theoretically, a known OD used to roll onto plates would give relatively consistent colony numbers on each experimental control plate. Numbers of colonies on lead contaminated plates could then be compared in a ratio-like fashion to the control plate for that experiment.

Got Lead? Case study

During the course of the project, the team developed a case study about synthetic biology, and lead pollution to help improve the understanding of the topic. We implemented our case study in the Introduction to Biotechnology course offered at WPI. The focus was how synthetic biology could be used to solve the problem of lead pollution. Students needed to look up what syntetic biology was, reasons for lead pollution, and interpret graphs and tables present in the power point. It went very well, and students had many creative answers to our questions.