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Name: Bashir N.
Status: Student
Age: 17
Location: N/A
Country: N/A
Date: 2001

What are the risks involved in growing bacteria on a agar plate?

As long as the bacteria stays on the plate there should be very little risk. Treat the cultures with respect, use aseptic technique when handling them. Dispose of them properly by either autoclaving or soaking them in 10% bleach for a few days and you should be fine. I wouldn't recommend using cultures of pathogens though, just for safety's sake.


The risk depends on what bacteria you grow. If these are non-pathogenic (that means they can not cause disease) there is no risk involved. If the bacteria are pathogenic (can cause disease) the handler has to take care not to get infected. That means not to get in touch with the bacterial growth (don't touch the surface of the agar with your hands), don't inhale aerosols (work in a ventilation cupboard), and sterilize the plates after use, so that the bacteria are not released in the environment.

This is Good Laboratory Practice (GLP) and, depending on the pathogenicity of the organism (how serious is the disease they can cause) extra biosafety levels are added. For instance, the room in which the experiments are conducted may have an atmosphere of under-pressure, so that any organisms that are released can not leave that room. If you'd be working at the highest biosafety level, you'd be wearing protective clothing and a shower were required before leaving the lab. But most bacteria are not, or only marginally, harmful.

Trudy Wassenaar
Curator of the Virtual Museum of Bacteria


Usually, there are minimal risks to people growing bacteria on a plate, because the laboratories where you grow them are set up to make sure that human health is protected. In class room settings, usually the instructors make sure that students are careful and also that the bacteria you work with are not those that cause disease. Additionally, all the infective materials are autoclaved to kill the organisms before they leave the laboratory. Otherwise, it could be hazardous, especially for laboratories that work to diagnose human and animal diseases. When bacteria are grown on agar, they are in higher concentrations and when plates are opened, there is the potential that some of the bacteria, fungi or their spores could be in the air and expose the people working with the agar plates if the laboratory is not properly equipped.

Laura Hungerford
University of Nebraska

Any bacteria can be a pathogen. Growing them in cultures is a little more dangerous because they are concentrated. Treat every bacterial culture with the same aseptic technique and caution.

Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy

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