Napkin Folding — biology
Controlling bacterial growth in fermentation with hurdle technology and survival analysis
Posted by Cameron Davidson-Pilon at
This article is a nice intersection of some of the topics I've been thinking about lately: bacteria, food, and survival analysis, and part of a larger project I've been working on (stay tuned). The bacteria C. Botulinum is responsible for creating one of the most dangerous chemicals known to man: botulinum toxin. If ingested, incredibly small amounts of this toxin can kill even a healthy person. Thankfully, food scientists and microbiologists have developed ways to control C. Botulinum. Any of...
Bayesian cell counting Pt. 2 - Growth over time
Posted by Cameron Davidson-Pilon at
I’ve started growing yeast in my closet-turned-laboratory. There’s a reason why I am growing yeast, but that’ll be for another post. For this experiment, I wanted to use my new hemocytometer to do cell counts periodically over the next few days to gather data.
A nutrient-rich bioreactor (an Erlenmeyer flask with wort) was left at room temperature with plenty of aeration (a magnetic stirrer) for about 2.5 days. My collected data is below.
Bayesian cell counting
Posted by Cameron Davidson-Pilon at
Let’s say you are interested in counting the concentration of cells in some sample. This is a pretty common task: sperm counts, blood cell counts, plankton counts. Microbiologists are always counting. Let’s use the example of yeast counting, which is traditional in beer and wine making. The brewery has a sample of yeast slurry, a highly concentrated amount of yeast, and they would like to know how concentrated it is, so they can add the correct amount to a batch....