Determining the mechanism of E. coli cell death

Althea Smith

Abstract:
Organic acids are weak acids commonly added to acidified foods as a
preservative agent. Unfortunately, when processing acidified foods there
is a risk of contamination by microbial pathogens. There have been recent
outbreaks of Escherichia coli O157: H7 (E. coli) in apple cider and the
FDA now requires a heating or pasteurizing step for all acidified foods.
It is currently believed that the mechanism, by which these bacteria are
killed, is due to lowering internal pH by accumulation of organic acid. We
present a mechanistic mathematical model, which predicts the mechanism
behind the killing of these deadly bacteria. By using this type of model,
the relative importance of various factors controlling the growth and
death of food pathogens by organic acids may be determined. Future work
includes experimentally measuring the internal pH of E. coli O157:H7and
comparing these values to model predictions. Severe health related issues
are presented when acidified food products are contaminated with deadly
bacteria and the continued development of this model will promote safe
food production.