INNOVATION, SCIENCE & TECHNOLOGY

A newly characterized circular bacteriocin has shown activity against Bacillus cereus, its biofilms and spore outgrowth, while outperforming nisin A under experimental conditions. The findings point toward a potentially valuable new preservation tool, but commercial food applications remain a much bigger test.

Key Takeaways

• A new circular bacteriocin, toyoncin WJY28, showed potency two to eight times higher than nisin A against Bacillus cereus under experimental conditions.
• It targets three hard-to-control microbial states at once: vegetative cells, biofilms and spore outgrowth, a broader profile than most antimicrobials demonstrate.
• It performed in a real food matrix, eliminating vegetative cells and spores in inoculated skim milk within 15 days, while remaining stable under pasteurization and pH stress.
• It is nowhere near replacing nisin commercially. Scale-up economics, food-matrix performance, resistance risk and regulatory approval remain unanswered.
• The bigger opportunity may be a broader library of narrow-spectrum bacteriocins engineered around specific pathogens and food systems, not a single nisin replacement.

Food preservation has always involved a difficult trade-off. Manufacturers need sufficient microbial control to protect food safety and shelf life, while formulation teams face demand for simpler ingredient systems and preservation approaches compatible with changing consumer expectations.

New research published in Food Research International introduces an intriguing candidate into that equation. Researchers have characterized toyoncin WJY28, a circular bacteriocin produced by Bacillus toyonensis WJY28. In laboratory testing, the compound demonstrated potent activity against the foodborne pathogen Bacillus cereus, with minimum inhibitory concentrations ranging from 0.39 to 0.78 micromolar, reported as two to eight times more potent than nisin A under the conditions investigated.

But potency alone is not what makes the research interesting. Toyoncin WJY28 attacked several forms of a microorganism that can be difficult to control.

The Challenge Is Bigger Than Killing Bacteria

Bacillus cereus is a spore-forming foodborne pathogen, a distinction that matters. Vegetative bacterial cells represent only one part of the microbial-control problem. Spores can survive environmental stresses that destroy actively growing cells, and biofilms present another challenge because microorganisms embedded within these communities become considerably harder to remove and control.

The researchers found that toyoncin WJY28 disrupted bacterial membranes in a concentration-dependent manner, producing bacteriostatic effects at lower concentrations and becoming bactericidal at higher ones. More importantly, it inhibited biofilm formation, killed cells within mature biofilms and prevented B. cereus spores from growing into vegetative cells, though it did not prevent initial germination itself.

A preservation technology capable of addressing vegetative cells, biofilm-associated cells and spore outgrowth could offer a broader microbial-control strategy than an antimicrobial demonstrated only against free-growing cells.

Then Came the Milk Test

Promising antimicrobial activity in a laboratory medium does not automatically translate into food preservation. Food is a considerably more complicated environment, where proteins, fats, carbohydrates and pH can all influence antimicrobial performance.

The researchers therefore tested toyoncin WJY28 in skim milk inoculated with B. cereus. At concentrations of 1.56 to 3.13 micromolar, the study reported elimination of vegetative cells and spores within a 15-day period. The bacteriocin also demonstrated stability under the pasteurization and pH conditions investigated, with no obvious hemolytic activity or cytotoxicity reported in the study’s safety assessments. These findings move the research beyond a basic antimicrobial-screening experiment, though they do not establish toyoncin WJY28 as a commercially ready food preservative.

Could It Really Challenge Nisin?

Nisin provides the obvious comparison because it is one of the best established bacteriocins used in food preservation, and its regulatory history shows why discovering an effective antimicrobial is only the beginning. In the United States, nisin preparation is recognized under 21 CFR 184.1538 for specified antimicrobial applications, including inhibiting Clostridium botulinum spore outgrowth and toxin formation in certain pasteurized cheese products. Canada also permits nisin as a preservative across specified applications, including certain egg products, beverages, meat products, smoked fish and refrigerated cooked potato-based products.

Toyoncin WJY28 has a long distance to travel before meaningful commercial comparisons with nisin can be made. The new research demonstrates biological potential, not regulatory approval, manufacturing economics or commercial equivalence.

The Real Commercial Questions Come Next

For ingredient companies and manufacturers, several questions now matter more than whether toyoncin WJY28 can inhibit bacteria in laboratory experiments. Can it be produced economically at industrial scale? Will it remain effective in high-fat, high-protein, acidic, salty and structurally complex foods? How will processing conditions affect its activity, and could microorganisms develop resistance after repeated exposure? What concentrations would be required, and would those affect flavour or texture? And critically, what toxicological and regulatory evidence would authorities require before approving its use?

Until questions like these are answered, describing toyoncin WJY28 as a replacement for nisin would be premature.

A Bigger Bacteriocin Opportunity

The significance of the research may extend beyond one molecule. Bacteriocins are antimicrobial peptides produced by bacteria, and circular bacteriocins are particularly interesting because their molecular structure can provide characteristics such as enhanced stability.

If researchers can identify bacteriocins with narrow but powerful activity against difficult foodborne microorganisms, preservation could become more targeted. Instead of expecting one preservative to control a broad microbial population, manufacturers could eventually access increasingly specialized antimicrobial systems designed around particular organisms, food matrices and processing environments. Toyoncin WJY28 is particularly interesting here because the researchers reported selective activity against B. cereus without harming the probiotic organisms evaluated, raising the longer-term possibility of preservation systems that become more microbiologically selective rather than simply more powerful.

What GFI Is Watching

The immediate story is not that nisin has found its replacement. It has not. The more important development is that scientists are expanding the library of antimicrobial molecules available for food preservation and targeting some of the hardest microbial states in food systems.

For manufacturers, that could eventually provide additional tools at a time when food safety, shelf-life requirements and formulation expectations are all moving simultaneously. Toyoncin WJY28 still needs considerably more research across food matrices, manufacturing conditions, toxicology, scale-up and regulatory pathways. But the combination demonstrated so far, vegetative cells, biofilms, spore outgrowth and food-system validation, is unusual enough to deserve attention. That makes this less a story about discovering another antimicrobial and more a glimpse at what the next generation of precision food preservation could look like.

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Sources

1. Gao, M., Liu, S., Li, F., Geng, C., Yang, C., Li, F., Zeng, H., Zhao, D., Xin, B. & Zeng, X. Understanding a novel circular bacteriocin with potent activity against Bacillus cereus, its biofilms, and spores for food preservation. Food Research International, 237, 119341, August 1, 2026.
2. U.S. Food and Drug Administration. Substances Added to Food: Nisin Preparation.
3. U.S. Code of Federal Regulations. 21 CFR §184.1538, Nisin preparation.
4. Health Canada. List of Permitted Preservatives.