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Microbes Are Everywhere

Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, Deanne B. Erdmann, MS, Sonia Rahmati Clayton, PhD, and James P. Denk, MA

Safety Considerations

It is important that students always think about safety when conducting a science investigation. This slide may be used to review safety with your class before starting the activity. Also, keep the following points in mind.

  • Always follow district and school safety guidelines.
  • Have a clear understanding of the investigation in advance (practice any investigation with which you are not familiar).
  • Continually monitor the area where the investigation is being conducted.


  • Do not allow students to test any body fluids for microbes, as these fluids might grow a disease-causing microbe. 
  • All supplies that come in contact with cultured microbes should be disinfected with a 10% chlorine bleach solution (10 mL chlorine bleach mixed with 90 mL water) and disposed of in accordance with district and school safety procedures. 
  • After the nutrient agar has been inoculated with the cotton swabs, seal the Petri dishes with masking tape to prevent exposure to the growing microbes. 
  • Before and after the activity, disinfect all work areas with a 10% chlorine bleach solution. 

Funded by the following grant(s)

Science Education Partnership Award, NIH

Science Education Partnership Award, NIH

Grant Number: 5R25RR018605