The experimental conditions were the same as GG20240831-1, but the media was not sterilized, as we hoped Saccharomyces cerevisiae would outgrow any contaminants due to the low pH. Unsurprisingly, the culture became contaminated early on, and a type of bacteria overgrew the yeast. We used this media to fine-tune the DO-STR PID, which was successful. With the previous settings (P=0, I=0.1, D=1), there was heavy fluctuation in both the DO and STR trendlines. However, with the new settings, the curves were completely flattened:

• P = 1
• I = 0.05
• D = 1

In the first 7.5 hours, there was a typical decrease in DO concentration. When the DO level reached 20%, the PID was activated, but there was heavy fluctuation. After the proper settings were introduced at 16.7 hours, the trendline flattened. Therefore, this setpoint will be used in the future for the 500 mL jFermi vessel.

Saccharomyces cerevisiae contaminant