Effect of gamma irradiation, high sugar content and antimicrobials on survival of Escherichia coli: A review

Abstract

Dried fruits are popular ready-to-eat snacks. However, due to cross-contamination or contact with infected persons, Escherichia coli could be present, of which some strains are pathogenic, thus, the consumption of contaminated dried fruits could pose a public health risk. Microbial cells subjected to stress factors such as osmotic shock, radiation and antimicrobials could induce complex stress response systems and adaptation. Radiation and antimicrobials have been shown to cause an SOS response in E. coli, which affects cellular metabolism, such as the enhanced ability to repair DNA and mutagenesis. Studies have shown that glucose plays a critical role in the down-or upregulation of locus for enterocyte effacement (LEE)-encoded virulence of E. coli. Gamma radiation could also cause the formation of viable but nonculturable (VBNC) cells. If these cells are present in a sample, the number of viable cells will be underestimated by the plate count method leading to the false conclusion that the product is germ-free. We have reviewed in this article how stressors such as high sugar content, gamma radiation, and antimicrobials affect the survival of E. coli in dried fruits.