Hypothetical question, intended to find a general procedure rather than case-specific recommendations:

I have a petri dish full of growth medium with a large population of gram-negative, anaerobic bacteria of numerous types growing in it. How would I go about replacing the existing population with lactobacillus and streptococcus strains?


  • The growth medium cannot be washed out of the petri dish
  • The petri dish cannot be treated with anything a human body can't handle, i.e. no blasting with bleach
  • After the procedure is complete, the original bacteria should have little to no chance of returning, even given months or years in the petri dish
  • $\begingroup$ Why would you want to do this? In the lab, you would simply throw the plate away and make sure it is autoclaved and you set up a new plate with the bacteria of interest. $\endgroup$
    – Chris
    Apr 11, 2016 at 7:34
  • $\begingroup$ Don't worry @Chris, I'm not running low on plates. The lab exists for the very purpose of modeling the real world, and yet in the real world you can't autoclave the environment. I can't for the life of me figure out a good way of replacing the bacteria in a real-world environment, so the purpose of this question is to discover how a trained biologist with years of experience and a touch of creativity would go about this. Think of it as a thought experiment $\endgroup$ Apr 11, 2016 at 7:43
  • $\begingroup$ Ah, ok, I wasn't sure of the purpose, thats why I asked. $\endgroup$
    – Chris
    Apr 11, 2016 at 7:56
  • $\begingroup$ Nobody has tried a procedure like this. Perhaps you can wipe the surface clean and wash it repeatedly with an antibiotic solution (a bactericidal one like streptomycin) + hydrogen peroxide (since the bacteria are anaerobic). I think all answers will be based on guess. $\endgroup$
    Apr 11, 2016 at 8:48
  • $\begingroup$ @WYSIWYG wiping the surface isn't allowed, as that wouldn't be possible in the equivalent real-world environment $\endgroup$ Apr 18, 2016 at 16:13


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