The antimicrobial activity of fermented whey was tested using a spot diffusion assay. In this assay, pathogenic bacteria of interest are incorporated into the agar plate and a spot of the whey is added to the surface. The plate is incubated to allow the pathogenic bacteria to grow. During incubation, the fermented whey diffuses into the agar and if it inhibits the pathogen a zone of clearing (no growth) is seen. By serial diluting the fermented whey, and spotting each dilution, a level of activity can be determined. To eliminate the affect of the high acid content of the fermented whey, we also conducted a second test by adjusting the pH to 7. This graph illustrates that there is antimicrobial activity in the fermented whey both with the low pH and a neutral pH.