October 1, 2018 (Vol. 38, No. 17)
Strong Points: Straightforward and easy to use
Weak Points: Users can’t save their calculations in the app
The MPN Calculator is a useful tool for biologists who need to estimate how many microorganisms they have in a sample. The app is fairly basic but is straightforward and easy to use for its designed purpose. After making serial dilutions of their samples, users can input into the app the number of tubes that are positive for the organism, the total number of tubes, and the volume inoculated within each tube. With this information, the app utilizes probability formulas to estimate the likely average density of microorganisms that are contained in the sample. In addition to providing the mean density, the app also gives users a 95% confidence interval of its calculation. The app includes detailed instructions on how to use it in order to get the best results and the app is well-referenced. The MPN Calculator is a useful tool for biologists at the bench who need to determine the density of organisms in their samples.