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Name: Bailey
Status: Other
Grade:  12+
Location: NE
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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