Natural antimicrobials fighting E. coli

The Natural Antibiotic You Didn't Know You Needed: Fighting E. coli with Nature's Power

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Could a blend of natural antimicrobials be the answer to combating dangerous E. coli strains and reducing reliance on traditional antibiotics?"

E. coli O157:H7 is a formidable foe, responsible for numerous foodborne outbreaks globally. This pathogen's ability to produce Shiga toxins in the human gut leads to severe clinical manifestations, including life-threatening hemolytic uremic syndrome. With conventional antibiotic treatments sometimes exacerbating the problem by increasing Shiga toxin production, researchers and the food industry are continuously seeking alternative control strategies.

Ruminants, particularly cattle, serve as significant reservoirs for E. coli O157:H7, frequently colonizing their lower gastrointestinal tracts. This presents a challenge to food safety, as contamination can occur during meat processing. Risk assessments have highlighted a direct link between the levels of E. coli O157:H7 in cattle feces and hides and the contamination of beef carcasses.

Against this backdrop, a promising strategy has emerged: leveraging natural antimicrobials to reduce pathogen levels and virulence within animals. A recent study delves into the efficacy of a commercial mixture of natural antimicrobials against E. coli O157:H7, potentially paving the way for innovative solutions in pre-harvest food safety.

Unlocking the Power of Natural Antimicrobials

The study, conducted by Stratakos et al. (2018), aimed to determine the effectiveness of a commercial mixture of natural antimicrobials against E. coli O157. This blend primarily consisted of lactic acid, citric acid, and citrus extract. The researchers sought to quantify the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the antimicrobial against E. coli O157:H7.

The results were compelling: the MIC was found to be 0.5% (v/v), while the MBC was 0.75% (v/v) of the natural antimicrobial. Further investigations into microbial growth kinetics revealed that the antimicrobial significantly impacted the pathogen's cell membrane. This was evidenced by increased relative electric conductivity and the release of proteins and nucleic acids. The antimicrobial's ability to reduce E. coli O157 concentrations in a model rumen system further underscored its potential.

Here are the key benefits uncovered:

Biofilm assays demonstrated that subinhibitory concentrations of the antimicrobial significantly reduced the biofilm-forming capacity of E. coli O157, without impeding pathogen growth. In addition, the natural antimicrobial was found to curtail motility and exopolysaccharide production, both vital for the pathogen's virulence. These results collectively indicate that the natural antimicrobial exerts a potent antimicrobial effect against E. coli O157 in vitro and within a model rumen system.

A Promising Future for Natural Solutions

These findings present a compelling case for the use of natural antimicrobials in controlling E. coli O157:H7 in animal populations, particularly ruminants. By reducing the pathogen load in the animal gut, the risk of contamination during meat processing can be significantly diminished, bolstering food safety and safeguarding public health. Further research is warranted to explore the long-term effects of these antimicrobials on rumen microbiota and to optimize their application in real-world settings. This research highlights the potential of natural antimicrobials as a valuable tool in the ongoing effort to combat foodborne pathogens and reduce our reliance on traditional antibiotics.

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This article is based on research published under:

DOI-LINK: 10.1089/fpd.2018.2465, Alternate LINK

Title: The Antimicrobial Effect Of A Commercial Mixture Of Natural Antimicrobials Against Escherichia Coli O157:H7

Subject: Animal Science and Zoology

Journal: Foodborne Pathogens and Disease

Publisher: Mary Ann Liebert Inc

Authors: Alexandros Ch. Stratakos, Mark Linton, Patrick Ward, Mairead Campbell, Carmel Kelly, Laurette Pinkerton, Lavinia Stef, Ioan Pet, Ducu Stef, Tiberiu Iancu, Katerina Theodoridou, Ozan Gundogdu, Nicolae Corcionivoschi

Published: 2019-02-01

Everything You Need To Know

What is E. coli O157:H7, and why is it a concern for food safety and public health?

E. coli O157:H7 is a dangerous strain of E. coli bacteria known to cause foodborne illness. It produces Shiga toxins in the human gut, leading to severe clinical manifestations such as hemolytic uremic syndrome, which can be life-threatening. Conventional antibiotic treatments can sometimes worsen the condition by increasing Shiga toxin production, making alternative control strategies like natural antimicrobials crucial.

What is the composition of the commercial blend of natural antimicrobials used in the study targeting E. coli O157:H7?

The commercial blend of natural antimicrobials primarily consists of lactic acid, citric acid, and citrus extract. This specific combination was studied for its efficacy against E. coli O157:H7. The research focused on determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the blend to understand its effectiveness.

What were the key findings regarding the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the natural antimicrobial against E. coli O157:H7?

The study found that the minimum inhibitory concentration (MIC) of the natural antimicrobial blend against E. coli O157:H7 was 0.5% (v/v), and the minimum bactericidal concentration (MBC) was 0.75% (v/v). This indicates the concentration at which the antimicrobial inhibits and kills the bacteria, respectively. Further studies showed that the antimicrobial impacts the pathogen's cell membrane, leading to the release of proteins and nucleic acids.

How does the natural antimicrobial blend affect the virulence and biofilm formation of E. coli O157:H7?

The natural antimicrobial blend was shown to reduce the biofilm-forming capacity of E. coli O157:H7, even at subinhibitory concentrations, without impeding pathogen growth. It also curtailed motility and exopolysaccharide production, which are vital for the pathogen's virulence. These effects significantly reduce the bacteria's ability to colonize and cause infection.

What are the implications of using natural antimicrobials in animals like cattle for controlling E. coli O157:H7, and what further research is needed?

Using natural antimicrobials in ruminants, like cattle, can reduce the levels of E. coli O157:H7 in their gastrointestinal tracts, thus decreasing the risk of meat contamination during processing. This approach enhances food safety and protects public health by preventing outbreaks of E. coli O157:H7. While promising, further research is needed to assess long-term impacts on rumen microbiota and optimize application in real-world settings.