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Bactericidal thurincin H causes unique morphological changes in Bacillus cereus F4552 without affecting membrane
Gaoyan Wang1, Guoping Feng, Abigail B Snyder
1Department of Food Science, Cornell University, Geneva, NY, USA.
FEMS Microbiology Letters
|June 4, 2014
Summary
Thurincin H, an antilisterial bacteriocin, effectively reduces bacterial viability without significantly permeabilizing cell membranes, unlike nisin. This study clarifies its unique mode of action against foodborne pathogens.
Area of Science:
- Microbiology
- Bacteriocins
- Food Safety
Background:
- Thurincin H is a hydrophobic, anionic bacteriocin from Bacillus thuringiensis SF361.
- It inhibits Gram-positive foodborne pathogens like Listeria monocytogenes and Bacillus cereus.
- Its unique structure, with thioether bonds, differs from other bacteriocins.
Purpose of the Study:
- To elucidate the mode of action of thurincin H.
- To compare its mechanism with well-characterized bacteriocins.
- To understand its potential as a food safety agent.
Main Methods:
- Bactericidal activity assays against Bacillus cereus F4552.
- Cell membrane permeability assays.
- Scanning electron microscopy (SEM) imaging.
- Comparison with nisin's mode of action.
Main Results:
- Thurincin H demonstrated bactericidal effects, reducing B. cereus viability by over 99%.
- No significant cell membrane permeability changes were observed with thurincin H, even at high concentrations.
- SEM showed intact B. cereus cells at 32 × MIC, with integrity loss only at 256 × MIC.
- Nisin induced significant membrane permeability at 2 × MIC.
Conclusions:
- Thurincin H possesses a distinct mode of action compared to pore-forming bacteriocins like nisin.
- Its mechanism does not rely on generalized membrane permeabilization.
- Thurincin H represents a novel class of bacteriocins with potential applications in food preservation.
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