A study published in Applied and Environmental Microbiology has identified Bacillus velezensis, a bacterial agent commonly used in agriculture, as the cause of a foodborne outbreak because of rope spoilage in cakes, marking the first documented case of illness linked to this biocontrol strain.
The outbreak occurred on May 12, 2024, during a business celebration at 11 sites in Greene County, OH, involving cakes from a small retail bakery. A survey of 35 employees found 12 reported mild enteric symptoms, including stomach aches, nausea, cramps, and diarrhea. Symptoms began between 25 minutes to 4.5 hours after consumption. Five patients experienced delayed diarrhea. No hospitalizations or deaths occurred. The Ohio Department of Health Laboratory confirmed B. velezensis in leftover cakes using VitekMS mass spectrometry, which identifies microbes by analyzing protein spectra.
Rope spoilage and bakery practices
Rope spoilage, known for over a century, causes a sweet, pineapple-like odor and stringy texture in baked goods. It has historically been linked to Bacillus subtilis and other Bacillus species. The study notes that taxonomic changes since 1973, which reclassified strains such as B. amyloliquefaciens subsp. plantarum into B. velezensis, may explain why B. velezensis has not previously been reported as a spoilage agent. The bacterium’s ability to grow at pH levels between 5 and 10 and water activity levels of 0.90 to 1.0 — conditions typical of cakes — enabled its growth and survival.
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