Study reveals impact of lantibiotic preservatives on gut microbiome

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Food manufacturers often add preservatives to food products to keep them fresh. A primary purpose of these preservatives is to kill microbes that might 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 like sodium benzoate, calcium propionate, and potassium sorbate.

Bacteria produce chemicals called bacteriocins to kill microbial competitors. These chemicals can act as natural preservatives by killing potentially dangerous pathogens in food. Lantipeptides, a class of bacteriocins with particularly strong antimicrobial properties, are widely used in the food industry and are known as “lantibiotics” (a scientific portmanteau of lantipeptide and antibiotic).

However, despite their widespread use, little is known about how these lantibiotics affect the gut microbiomes of people who consume them. Microbes live in a delicate balance in the gut, 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 by disinfectant food preservatives, opportunistic pathogenic bacteria can take their place and wreak havoc—resulting in nothing better than eating the contaminated food in the first place.

Effects on good and bad bacteria

A new study has been published ACS Chemical Biology University of Chicago scientists have discovered that one of the most common classes of lantibiotics has powerful effects against pathogens and the normal 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 human gut microbes also produce similar lantibiotics. Zhenrun “Jerry” Zhang, PhD, a postdoctoral scholar in the lab of Eric Palmer, MD, Donald F. Steiner, professor of medicine and director of the Dukosois Family Institute in UChicago, wanted to study the effects of such naturally occurring lantibiotics on commensal gut bacteria.

Nisin is basically an antibiotic that has long been added to our diet, but how it might affect our gut microbes has not been well studied. While this can be very effective in preventing food contamination, it can also have a greater impact on our human gut microbes.”


Zhenrun “Jerry” Zhang, PhD, Postdoctoral Scholar

He and his colleagues mined a public database of human gut bacterial genomes and identified genes for making six different gut-derived lantibiotics that closely resemble nisin, four of which were new. Then, Wilfred A. Richard E. van der Donk, Ph.D., in chemistry at the University of Illinois at Urbana-Champaign. In collaboration with the Heckert Endowed Chair, they developed versions of these lantibiotics to test their effects on both pathogens and commensal gut bacteria. The researchers found that while different lantibiotics had different effects, they killed pathogens and commensal bacteria similarly.

“This study is the first to show that gut commensals are sensitive to lantibiotics and sometimes more sensitive than pathogens,” Zhang said. “With the levels of lantibiotics in food now, it’s very likely that it could affect our gut health as well.”

Harnessing the power of lantibiotics

Zhang and his team studied the peptide structure of lantibiotics to better understand their activity, in the interest of learning how to better harness their antimicrobial properties. For example, in another study, the Palmer lab showed that a consortium of four microbes, including one that produces lantibiotics, helped protect mice from antibiotic-resistance. Enterococcus Infection They are also studying the prevalence of lantibiotic-resistant genes in people from different populations to see how such bacteria can colonize the gut under different conditions and diets.

“It appears that lantibiotics and lantibiotic-producing bacteria are not always good for health, so we are looking for ways to counter the potential ill effects while taking advantage of their more beneficial antimicrobial properties,” Zhang said.

Source:

Journal Reference:

Zhang, Z.J., etc (2024). Activity of gut-derived nisin-like lantibiotics against human intestinal pathogens and commensals. ACS Chemical Biology. doi.org/10.1021/acschembio.3c00577.



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