Searching for Organic Antimicrobials

Organic food production in Washington State is expanding rapidly. However, this industry is hampered by the lack of effective antimicrobial agents which can be used in organic food production. Plants rely on innate immunity to defend microbial invasion, depending on the antimicrobial effects of phytocompounds. Plants (herbs) with high antimicrobial contents were used to treat infections since ancient times, though their use in recent decades has been largely abandoned due to the discovery of antibiotics. However, these phytochemicals are excellent candidates for developing organic antimicrobials to treat infection in organic livestock, in particular cow mastitis. Dandelion has long been used as an antimicrobial herb to treat mastitis, but its antimicrobial compounds have not been characterized. We plan to develop an effective extraction method to isolate these antimicrobial compounds from Dandelion and to further test their efficacy in inhibiting the growth of pathogens causing cow mastitis, focusing on Staphylococcus aureus and E. coli. The development of effective phytochemical extracts against microbial infection, so called “organic antimicrobials”, will facilitate the development and profitability of organic farming, further boosting the prosperity of organic agricultural industry at Washington State and the US.

Grant Information

  • Project ID: 136
  • Project Status: Complete


  • Principal Investigator(s): Zhu, M.
  • Investigator(s): Du, M., Fox, L., Killinger, K., Zhang, S.
  • Grant Amount: $40,000
  • 2014 Progress Report (PDF)


1. Sheng, L., M. J. Zhu. 2014. Inhibitory effect of Cinnamomum cassia oil on nonO157
Shiga toxin-producing Escherichia coli. Food Control, 46: 374-381.
2. Zhu H., M. Du, L. Fox, M. J. Zhu. 2015. Bactericidal effects of Cinnamomum cassia
oil against bacterial pathogens of bovine mastitis. Submitted to Food Control.
3. Zhang S., L. Sheng, M. Du, L. Fox, M. J. Zhu. 2015. Antioxidants and antimicrobial
activity of dandelion extracts. Submitted to International Journal of Pharmacology
and Phytochemistry

Additional Funds Leveraged

Using the data generated we are planning to submit proposals to USDA Food Safety,
USDA Organic Transitions (USDA‐ORG) and/or USDAOREI program in 2016.


Short-term: We have formed an effective multidisciplinary team that covers food
microbiology, animal science and pathology, and extension in developing new natural
antimicrobials. Through proposed studies, we have demonstrated the effectiveness of
natural antimicrobial extracts in the inhibition of pathogens associated with mastitis.
Long-term: Our long-term objective is to develop an effective organic antimicrobial
cocktail which can be used as an antibiotic alternative for organic food production.
Successful use of organic antimicrobials will reduce pathogen contamination and
prevalence in organic foods, improving the wholesomeness of organic food products, as
well as the profitability of organic farm operation.