Evaluating the Biocontrol Potential of <i>Bacillus subtilis</i> Spores Against <i>Listeria monocytogenes</i> in Tryptic Soy Broth and Hummus
This study evaluated the antimicrobial potential of a <i>Bacillus subtilis</i> spore-based probiotic cocktail to reduce foodborne pathogens in both nutrient-rich laboratory media and a complex food matrix (hummus). Three common foodborne pathogens—<i>Listeria monocytogenes</i>...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Applied Microbiology |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2673-8007/5/2/47 |
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| Summary: | This study evaluated the antimicrobial potential of a <i>Bacillus subtilis</i> spore-based probiotic cocktail to reduce foodborne pathogens in both nutrient-rich laboratory media and a complex food matrix (hummus). Three common foodborne pathogens—<i>Listeria monocytogenes</i>, <i>Escherichia coli</i> O157:H7, and <i>Salmonella</i> Typhimurium—were cultured individually in full-strength, half-strength, and quarter-strength tryptic soy broth (TSB) with or without the probiotic spores (~7 log CFU/mL). Additionally, a commercial hummus formulation was inoculated with <i>L. monocytogenes</i> (~3 log CFU/g) and <i>B. subtilis</i> spores (~7 log CFU/g) and stored at 30 °C to simulate temperature abuse. In TSB, <i>E. coli</i> and <i>Salmonella</i> grew to ~8.2 log CFU/mL in full-strength media, with no significant inhibition by the probiotics. However, <i>L. monocytogenes</i> showed substantial suppression: in nutrient-limited TSB, viable counts dropped below the detection limit of 1.48 log CFU/mL by 24 h in the presence of probiotics. In hummus, <i>L. monocytogenes</i> grew to an average of 8.22 log CFU/g in the absence of probiotics but remained significantly lower at an average of 5.03 log CFU/g when co-inoculated with <i>B. subtilis</i> (<i>p</i> < 0.05). Germination of probiotic spores was confirmed within 6 h under all conditions. These findings suggest that <i>B. subtilis</i> spores selectively inhibit <i>Listeria</i>, particularly under nutrient stress or abuse conditions. While the probiotic had limited impact on Gram-negative pathogens, its application may serve as a clean-label strategy for suppressing <i>L. monocytogenes</i> in ready-to-eat (RTE) foods. This dual-model approach provides insights into both mechanistic activity and practical limitations of spore probiotics in complex food matrices. |
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| ISSN: | 2673-8007 |