A Diffusion Model to Quantify Membrane Repair Process in Listeria monocytogenes Exposed to High Pressure Processing...

Area of Science:

• Microbiology
• Food Science
• Biophysics

Background:

• Cellular responses to environmental stresses are well-documented.
• High pressure processing (HPP) is an emerging food preservation technique.
• Microbial damage and response to HPP remain poorly understood.

Purpose of the Study:

• To investigate the cellular damage and repair mechanisms of *Listeria monocytogenes* following HPP exposure.
• To quantitatively characterize the plasma membrane pores induced by HPP.
• To model the dynamic changes in membrane integrity post-HPP.

Main Methods:

• Exposure of *Listeria monocytogenes* to HPP (400 MPa, 8 min, 8°C).
• Propidium iodide (PI) staining and high-frequency fluorescence microscopy to monitor membrane permeability.
• Development and calibration of a mathematical dynamic model based on mass transfer and diffusion laws.

Main Results:

• HPP induced plasma membrane pores in *Listeria monocytogenes*.
• PI diffusion into cells decreased over four days, indicating pore repair.
• The mathematical model revealed a temporal decrease in pore size, suggesting closure.
• Membrane repair occurred linearly, with temporary growth arrest at the population level.

Conclusions:

• This study provides the first quantitative description of pressure-induced membrane pores and their time-dependent reduction.
• A subgroup of bacteria survived HPP through active membrane repair, exhibiting sub-lethal injury.
• The findings highlight the dynamic repair processes in bacteria recovering from HPP stress.