Date of Graduation


Document Type


Degree Name

Bachelor of Science in Chemical Engineering

Degree Level



Chemical Engineering


Beitle, Robert


Genetic engineering of living organisms provides the opportunity to express and harvest different proteins from cell surfaces. Yeast (S. cerevisiae) is one such organism and is capable of being grown on an industrial scale. Cellular concentration is an important parameter to monitor while fermentation processes are underway, in order to control the environment inside the growth medium and maximize yields. Spectrophotometry is a conventional method for measuring concentration, but is limited by a narrow absorbance range, and the need for on-site periodic sampling. A continuous method of measurement, as provided by Bug Labs BE2100 non-invasive biomass monitor, would allow for remote monitoring of cell concentration, and an increased sampling rate. Previous studies on the use of the “BugEye” as a continuous measurement device for E. coli growth failed to yield a simple correlation between absorbance measurements using a spectrophotometer and the Bug Unit of the BE2100. This study aims to monitor fermentation of S. cerevisiae and produce a useful correlation between optical density from a spectrophotometer and the BugEye output. The results were not conclusive on a definite conversion; however, strong linearity and minimal error was found between the two measurements. Further research is likely to quantify their relationship.


BugEye, S. cerevisiae, optical density, Bug Units, bioreactor, fermentation