Design Problems in Microbiology at Home Labs

Today while discussing on how to culture bacteria at Home Labs using potato slices, there were several issues came up while discussing the experimental setup.
The issues such as what is a bacterial colony? How to get a bacterial colony? How to identify its a milk bacteria or contaminant?

Some design problems which came up from conversation between @_Seema_11 and @Ryle D’souza in culturing bacteria on potato slice are as follows:

  1. How to streak on potato to get pure colony?
  2. How to make a control?
  3. How many slices to be made from single potato?
  4. Whether to streak dilute or undiluted sample?
  5. Should both test and control be kept in same container or separate ones?

Setup of @Ryle D’souza showing setups of Home Labs to culture bacteria on potato slice, and identifying single isolated colonies.

This is a setup after 48hrs, where some cottony growth is visible, @Ryle explained it is fungus, @_Seema_11 asked whether milk has fungus? It was later discussed how Control can help us to know if colonies are from milk or from contamination. Thus we understood the importance of Controls in experiments.

Following is the setup designed in discussion in Chatshalla where in ‘Test’ milk sample is streaked in S-shaped, and controls are without milk sample streak.

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