Lysozyme as a barrier to growth of Bacillus anthracis strain Sterne in liquid egg white, milk and beef

Food Microbiol. 2011 Sep;28(6):1231-4. doi: 10.1016/j.fm.2011.03.002. Epub 2011 Mar 11.

Abstract

In this study, we investigated the role of lysozyme on the viability of Bacillus cereus, Bacillus subtilis, Bacillus pumilus and Bacillus anthracis (Sterne) in egg white (EW), ground beef and milk. At 35 °C in EW, growth rates (GR) for B. cereus, B. subtilis, B. pumilus and B. anthracis were 0.005, -0.018, -0.028 and -0.029 OD(600)/h, respectively. Heat-treating EW at 55 and 60 °C reduced the inactivating effect of EW by 3.1 and 10.5-fold, respectively. Addition of lysozyme (2 mg/ml) to 60 °C-treated EW increased the inactivation rate 5.76-fold, indicating involvement of lysozyme in B. anthracis inactivation. B. anthracis inactivation was influenced by pH, as shown by a progressive increase in inactivation rate from 0.25 to -4.42 logs CFU/h over a pH range of 6.0-8.5. Adding 2 mg/ml lysozyme to milk and ground beef also suppressed the growth of B. anthracis 3.3 and 6.5-fold, respectively. These data indicate that lysozyme, as a natural component of EW or potential additive in other foods, could reduce biothreat risks presented by bioterror agents.

Publication types

  • Evaluation Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacillus anthracis / drug effects
  • Bacillus anthracis / growth & development*
  • Bacillus anthracis / isolation & purification
  • Cattle
  • Egg White / microbiology*
  • Food Preservation / methods*
  • Food Preservatives / pharmacology*
  • Hot Temperature
  • Meat / microbiology*
  • Microbial Viability / drug effects*
  • Milk / microbiology*
  • Muramidase / pharmacology*

Substances

  • Food Preservatives
  • Muramidase