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Ask a biosafety officer

What species of microorganisms are safe to use at home and what is the preferred method of inactivating or destroying them?

Answer from a Biosafety Officer:

June 10, 2013

Risk group 1 organisms are defined by most guidelines as those that do not usually cause disease in healthy adults (1), and these microorganisms are often used in teaching laboratories (2).  Some resources that will help you identify risk group 1 organisms include the NIH Guidelines for Research Involving Recombinant or Synthetic Nucleic Acids (3:  Appendix B:  Classification of Human Etiologic Agents on the Basis of Hazard), the ABSA Risk Group Database (1), and the Public Health Agency of Canada Pathogen Safety Data Sheets (4). 

It is important to know that although risk group 1 microorganisms do not usually cause disease in healthy adults, they can pose a risk for infants and children, the elderly, and immunocompromised individuals (2).  It’s very important to make sure that all of your work area surfaces are properly disinfected and separated from food preparation and living areas.  Standard microbiological practices, as described in the BMBL (2) and the ASM Guidelines, should be practiced to minimize the risk of opportunistic infection for you and those around you.

The preferred method of inactivating pathogens in the laboratory is by autoclaving.  However, Clorox bleach is an effective disinfectant that is readily available.  Cultures should be treated with a 1:10 dilution of Clorox bleach (1 part bleach to 9 parts liquid culture e.g. 10 mL bleach in 90 mL liquid culture) (5-7).  The surfaces of petri dishes can be soaked in a 1:10 dilution of Clorox bleach for 2 hours before disposal (8).  Decontaminate your work area when you are finished working. Make sure that all surfaces that you want to disinfect remain wet with the diluted bleach solution for at least 10 minutes (5).  Fresh dilutions of bleach should be made daily. 



1.     American Biological Safety Association Risk Group Database.  Accessed 03/01/2013.

2.     Wilson, D., and L. Chosewood, editors.  Biosafety in Microbiological and Biomedical Laboratories (BMBL), 5th edition.  Centers for Disease Control and Prevention and National Institutes of Health.  2009.  Accessed 03/03/2013.

3.     NIH Guidelines for Research with Recombinant or Synthetic Nucleic Acid Molecules.  March 2013.  Accessed 03/03/2013.

4.     Public Health Agency of Canada.  Pathogen Safety Data Sheets and Risk Assessment.  Accessed 03/03/2013.

5.     3M.  Disinfection with Bleach Tech Talk.  June 2011.  Accessed 03/03/2013.

6.     Dvorak, G.  Disinfection 101.  The Center for Food Security and Public Health, Iowa State University.  2008.  Accessed 03/03/2013.

7.     Sehulster, L., and R. Chinn.  Guidelines for Environmental Infection Control in Health-Care Facilities.  MMWR.  52(RR10): 1-42, 2003.  Accessed 03/03/2013.

8.     American Society for Microbiology.  Draft Guidelines for Biosafety in Teaching Laboratories.  2012.  Accessed 03/03/2013.