Synergistic effect of high-pressure thermal sterilization and muramidase on Bacillus subtilis spores: alterations in
Jiajia Li1,2, Weishan Xin1, Dunhua Liu1
1College of Food Science and Engineering, Ningxia University, Yinchuan, 750021, China.
Abstract:
The sporicidal mechanism of high-pressure thermal sterilization (HPTS) combined with muramidase against Bacillus subtilis spores was investigated. Results demonstrated that HPTS at 600 MPa/75°C with 0.3% muramidase achieved a 6.09 log reduction in Bacillus subtilis spores. The combined processing significantly increased the leakage of protein, nucleic acid, and dipicolinic acid, while significantly reducing Na+/K+-ATPase activity (P < 0.05). Scanning electron microscopy revealed notable morphological changes in spores after combined processing. A significant increase in propidium iodide (PI)-infiltrated spores indicated enhanced spore inner membrane permeability (P < 0.05). molecular composition analysis further showed disordered arrangement of fatty acid acyl chains, structural alterations in nucleic acids and proteins, and increased the peptidoglycan layer flexibility. These findings provided insights into the sporicidal mechanism of HPTS combined with muramidase.
Insights
High-pressure thermal sterilization combined with muramidase effectively inactivates Bacillus subtilis spores. This process damages spore structures, increasing permeability and leading to significant cell death.
Area of Science:
- Microbiology
- Food Science
- Biotechnology
Background:
- Bacterial endospores, like Bacillus subtilis, are highly resistant to conventional sterilization methods.
- Understanding spore inactivation mechanisms is crucial for food safety and sterilization technologies.
Purpose of the Study:
- To elucidate the sporicidal mechanism of combining high-pressure thermal sterilization (HPTS) with muramidase.
- To investigate the effects of this combined treatment on Bacillus subtilis spore integrity and viability.
Main Methods:
- Bacillus subtilis spores were treated with HPTS (600 MPa/75°C) and 0.3% muramidase.
- Assessed spore reduction, leakage of intracellular components (protein, nucleic acid, dipicolinic acid), and Na+/K+-ATPase activity.
- Utilized scanning electron microscopy (SEM) for morphological analysis and propidium iodide (PI) staining for membrane permeability.
Main Results:
- Achieved a 6.09 log reduction in Bacillus subtilis spores with the combined treatment.
- Significantly increased leakage of cellular components and Na+/K+-ATPase inactivation.
- Observed significant morphological damage, enhanced inner membrane permeability (PI infiltration), and altered molecular composition.
Conclusions:
- HPTS combined with muramidase exhibits a potent sporicidal effect against Bacillus subtilis.
- The mechanism involves disruption of spore structure, increased membrane permeability, and damage to essential cellular components.
- This synergistic approach offers a promising method for spore inactivation in relevant applications.
Related Concept Videos
01:29Methods of Sterilization I: Physical Methods
Steam sterilization uses non-toxic, low-cost moist heat in the form of saturated steam under pressure, which is fast, microbicidal, and sporicidal, and quickly warms and penetrates fabrics. Autoclaves, or steam sterilizers, expose each item to direct steam contact for a predetermined time at the necessary...
01:30Methods of Sterilization II: Chemical Methods
Using chemical sterilization rather than heat to clean out equipment is recommended. It eradicates and removes all bacteria,...
01:27Combined Effects of Drugs: Synergism
Such synergistic combinations...