Correlating beta-lactamase expression to absorbance
In the &beta;-lactamase test, an inhibitor of &beta;-lactamase is added to a sample of the culture medium. The inhibitor binds to the enzyme and changes its color, which is in direct correlation to the concentration of the &beta;-lactamase. More &beta;-lactamase means more inhibitor binding and this results in more color development leading to a higher absorption. So higher absorption means more &beta;-lactamase in the supernatant.