Viable Plate Count… or how to count to a million

Learning Outcomes

When you have completed this module, you should be able to:

  • Define dilution and dilution factor
  • Explain why dilutions are necessary for microbial counts
  • Prepare dilutions and calculate total dilution of serial dilutions
  • Set up an appropriate dilution scheme to result in a countable plate
  • Evaluate and interpret the results of plate counts, including selecting the appropriate plate for counting and scaling up from the diluted sample to the original population
1: Why we need to dilute
2: Setting the stage: Diluting Cold Press Coffee
3: Working out the dilution
4: Overall dilution
5: Design a dilution scheme
6: How to scale up
7: Count a plate!
8: Why we plate more than one dilution?
9: Picking the plate to count
10: Putting it all together
11: Quickies
12: Is the water safe?
13: Summary