Pressure inactivation kinetics of phage lambda cI 857

Area of Science:

• Microbiology
• Food Science
• Biophysics

Background:

• Bacteriophages, such as phage lambda, are viruses that infect bacteria and can impact food production.
• High hydrostatic pressure (HHP) is a non-thermal processing method used for microbial inactivation.
• Understanding phage inactivation kinetics is crucial for ensuring food safety and process efficacy.

Purpose of the Study:

• To investigate the inactivation kinetics of phage lambda cI 857 under high hydrostatic pressure.
• To evaluate the suitability of different mathematical models for describing phage inactivation curves.
• To assess the influence of menstruum composition on phage pressure resistance.

Main Methods:

• Phage lambda was subjected to high hydrostatic pressure (300-400 MPa) in buffered media and milk.
• Phage titers were measured over time to generate inactivation curves.
• Linear and nonlinear models (Weibull, log-logistic, modified Gompertz) were fitted to the data.

Main Results:

• HHP treatment significantly reduced phage lambda titers, with inactivation dependent on pressure and duration.
• Tailing was observed in inactivation curves, indicating the inadequacy of linear models.
• The Weibull and log-logistic models provided the best fit for inactivation data.
• A simplified Weibull model, with a fixed shape parameter, offered comparable fits and predictive potential.
• Menstruum composition significantly influenced phage lambda's pressure resistance, with phage lambda being more sensitive than Hepatitis A virus.

Conclusions:

• High hydrostatic pressure is an effective method for inactivating phage lambda.
• Nonlinear models, particularly the Weibull model, are suitable for describing phage inactivation kinetics under pressure.
• The composition of the processing medium plays a significant role in phage pressure resistance.
• Phage lambda exhibits greater pressure sensitivity compared to Hepatitis A virus in specific media.