There may be merit to the old adage “you are what you eat” — Feeding probiotics to livestock could combat antibiotic resistance in humans.
One Purdue professor is harnessing the antimicrobial powers of gut bacteria — organisms known as probiotics — to target pathogens.
“They can help improve animal or human health by … creating a positive environment that really helps the host cells in the gut to become more active,” said Arun Bhunia, a professor in food microbiology in a phone interview. “The body has a better capacity to overcome any disease by pathogens.”
According to a 2015 study by the National Center for Biotechnology Information, 62% of protein intake comes from animal or dairy sources. Keeping those animals healthy is pertinent, as harmful animal microbes can be ingested by humans and enter the body.
“If any of those microbes develop antibiotic resistance and those microbes are in your body and making you sick,” Bhunia said, “you could go to a doctor and they will try to prescribe an antibiotic, but they will find out the antibiotic is not working.”
The Food and Drug Administration has taken measures to prevent harmful transfer from animals to humans. In 2017, the FDA banned the use of “medically important antibiotics” as growth promoters for food animals.
Bhunia argues these measures will not be enough to tackle antibiotic resistance. Using probiotics could be a preventive measure to make animals healthier and stronger.
Rishi Drolia, a postdoctoral research associate in Bhunia’s lab, said in a phone interview that existing probiotics are difficult to control and do not permanently stay in the digestive tract.
“The biggest problem with probiotics is that they don’t stay in the gut for long,” Drolia said. “That’s the reason why if we engineer the probiotic, it makes the efficacy of the probiotic to survive and attach to the gut better.”
Bhunia and his team bolster naturally occurring organisms to be more effective at protecting the animal against disease. In one case, Bhunia took a protein which the foodborne pathogen Listeria monocytogens uses to attach itself to cells and put it on a probiotic.
“We want to colonize the whole body with that probiotic and bind to the place where Listeria could bind,” Bhunia said. “If there’s a chair in a room and there are two people in the room, it’s whoever sits there first, right?”
Unlike antibiotics which kill harmful bacteria, probiotics use multiple means to competitively exclude pathogens from infecting the body.
“It enhances the intestinal barrier function. It makes the intestinal cells more strong,” Drolia said.
The ability for probiotics to use numerous methods makes it difficult for bad bacteria to develop resistance to the probiotics.
Bhunia said a lot of care is taken to make sure the the bioengineered probiotics are safe and nonintrusive.
“We do a lot of content work to understand the protein well and what does it do,” Bhunia said. “As soon as we put it in the probiotic we are doing in-depth experimental research ... to demonstrate it does not have any unintended consequences.”
Future work will look at how probiotics can be used to prevent chronic inflammatory conditions and apply the technology to larger animal models.
A lot of energy is required to find new methods to fight nature’s smallest organisms. Sometimes, it means using them against each other.
“Microbes are very, very tough organisms,” Bhunia said. “They are very small, they are single-celled, but they know how to overcome all these problems. They want to survive — like us.”