Zone of Inhibition
Country: United States
Date: March 2009
How can you determine whether the zone of inhibition is due to
death of a bacterium or to inhibition of growth?
If the compound you are testing is bacteriocidal, you will not be able to recover
bacteria from the zone of inhibition. If the compound is only bacteriostatic, you
should be able to recover bacteria from the zone of inhibition by scraping the
surface of the agar and resupending the scrapings in sterile saline and then
spreading an aliquot of the suspension on nutrient agar that does not contain
the bacteriosttic agent.
Ron Baker, Ph.D.
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Update: June 2012