Common food preservative has unexpected effects on the gut microbiome

Food manufacturers often add preservatives to food products to keep them fresh. A primary purpose of these preservatives is to kill microbes that could break down and otherwise spoil the food. Common additives like sugar, salt, vinegar and alcohol have been used as preservatives for centuries, but modern-day food labels now reveal more unfamiliar ingredients such as sodium benzoate, calcium propionate, and potassium sorbate.

Bacteria produce chemicals called bacteriocins to kill microbial competitors. These chemicals can serve as natural preservatives by killing potentially dangerous pathogens in food. Lanthipeptides, a class of bacteriocins with especially potent antimicrobial properties, are widely used by the food industry and have become known as “lantibiotics” (a scientific portmanteau of lanthipeptide and antibiotics).

Despite their widespread use, however, little is known about how these lantibiotics affect the gut microbiomes of people who consume them in food. Microbes in the gut live in a delicate balance, and commensal bacteria provide important benefits to the body by breaking down nutrients, producing metabolites, and—importantly—protecting against pathogens. If too many commensals are indiscriminately killed off by antimicrobial food preservatives, opportunistic pathogenic bacteria might take their place and wreak havoc—a result no better than eating contaminated food in the first place.

A new study published in ACS Chemical Biology by scientists from the University of Chicago found that one of the most common classes of lantibiotics has potent effects both against pathogens and against the commensal gut bacteria that keep us healthy.

Nisin is a popular lantibiotic used in everything from beer and sausage to cheese and dipping sauces. It is produced by bacteria that live in the mammary glands of cows, but microbes in the human gut produce similar lantibiotics too. Zhenrun “Jerry” Zhang, PhD, a postdoctoral scholar in the lab of Eric Pamer, MD, the Donald F. Steiner Professor of Medicine and Director of the Duchossois Family Institute at UChicago, wanted to study the impact of such naturally-produced lantibiotics on commensal gut bacteria.

“Nisin is, in essence, an antibiotic that has been added to our food for a long time, but how it might impact our gut microbes is not well studied,” Zhang said. “Even though it might be very effective in preventing food contamination, it might also have a greater impact on our human gut microbes.”

Reference: Common food preservative has unexpected effects on the gut microbiome; ACS Chemical Biology, DOI: 10.1021/acschembio.3c00577