Inactivation Mechanism of Aspergillus flavus Conidia by High Hydrostatic Pressure

Area of Science:

• Food microbiology
• Microbial inactivation
• High hydrostatic pressure technology

Background:

• Aspergillus flavus poses significant risks in food safety and spoilage.
• Effective inactivation methods for fungal spores are crucial for preventing contamination.
• Understanding the inactivation mechanisms is key to optimizing food preservation techniques.

Purpose of the Study:

• To elucidate the inactivation mechanism of Aspergillus flavus conidia using high hydrostatic pressure (HHP).
• To investigate the effects of HHP on fungal spore morphology and protein composition.
• To determine the pressure and time parameters required for complete fungal inactivation.

Main Methods:

• Assessing fungal inactivation through activity counts and spore viability.
• Utilizing scanning electron microscopy (SEM) to visualize morphological changes.
• Employing SDS-PAGE to analyze alterations in protein composition.
• Measuring Propidium Iodide absorption to correlate with spore viability.

Main Results:

• A 3-minute HHP treatment at 600 MPa completely inactivated 10^7 CFU/mL of Aspergillus flavus conidia.
• SEM analysis revealed HHP-induced morphological disruption and pore formation, leading to intracellular molecule release.
• Increased Propidium Iodide absorption correlated with decreased spore viability.
• SDS-PAGE indicated partial protein degradation and extracellular release of proteins following HHP treatment.
• Nucleic acid and protein concentrations in the suspension increased with rising treatment pressure.

Conclusions:

• HHP induces morphological damage to both internal and external cellular structures of Aspergillus flavus conidia.
• HHP treatment leads to the degradation and release of intracellular and extracellular proteins, resulting in fungal inactivation.
• HHP is a viable technology for achieving complete inactivation of Aspergillus flavus conidia.