How do pH levels affect E. coli growth? Carly Bates, a third-year student at Iowa State University College of Veterinary Medicine, answered this question during the Allen D. Leman Swine Conference in her presentation, “How low should the pH go? How pH levels affect E. coli growth.” On Sept. 18, she was awarded the 2023 Morrison Swine Innovator Prize, an award given to veterinary students who want to specialize in swine medicine.
“This summer I got to spend a lot of time in barns and at sites that were unfortunately suffering from E. Coli breaks,” Bates explains. “I got to see firsthand the devastations that this disease can cause on producers, caretakers and even the vet team. Seeing all this, I knew I wanted to focus one of my summer projects on being able to help the swine industry prevent and decrease the effects of E. Coli, especially in the face of many anti-microbial resistant strains.”
Bates studied the growth of F18 Escherichia coli at various pH levels. F18 E. coli typically affects post-weaning pigs around 10-12 weeks of age and has a mortality rate between 50% and 90%.
“This project was fairly simple in evaluating how low the pH of E.coli’s environment should go in order to decrease/prevent growth. I altered the pH of tryptic soy broth (TSB) using lactic acid to achieve a pH of 3,4,5,6 and 7. From there I took one colony of E. Coli and placed it in the TSB and incubated for 24 hours. After those 24 hours, I diluted the original inoculum at 1:10 all the way to a 1:100,000 dilutions and plated all of these dilutions including the original inoculum and evaluated growth after 12 hours of the plates being incubated. The plates were evaluated using visual surface growth,” Bates says.
She says the most important takeaway from this study is that growth of E. Coli is strongly prevented/decreased at a pH of 4. There was no surface growth seen on any of the plates at a pH of 3 or 4 which indicates that at these pH levels E. Coli growth in inhibited.
“This project can help producers as we face many challenges with E. Coli such as anti-microbial resistance and workforce shortages. Water acidifying products are becoming more popular in the swine industry today and this projects helped to narrow in on a target level that we can encourage producers to reach in the water when using these acidifying products to see an affect. These products are easy to use, can be ran on a whole herd level to help fight E. Coli without anti-microbial use,” Bates explains.
In addition to complimentary registration and travel costs to attend the Leman Swine Conference, Bates received a cash award of $5,000. The Morrison Swine Innovator Prize honors the legacy of the late Bob Morrison, DVM, who coordinated the conference for many years. The prize is sponsored by leading swine producers, veterinary practices and industry partners.
“The jury felt like Carly was really confident in her delivery, had ownership of the content, and understood her project well. Her findings could easily be applied to a farm and had a clear take-away message,” Perle Zhitnitskiy, UMN professor who coordinates the Morrison Swine Innovator Prize, said in a release.
More from the Leman Swine Conference:
Assume the Barn Has Disease Even If It Doesn’t
Thoughts Worth Repeating from the 2023 Leman Swine Conference
Developing Replacement Gilts: How to Nourish Your Long-Term Investment
