Control of Listeria monocytogenes and Heat-Resistant Escherichia coli on Vacuum-Packaged Beef

• Author / Creator

  Socholotuik, Mandi R

• Novel methods to control Listeria monocytogenes and Escherichia coli on vacuum-packaged raw beef were investigated. Bacteriocin-negative Lactobacillus sakei FUA3058 and bacteriocin-positive Carnobacterium maltaromaticum UAL307 were tested as biopreservatives, alone or in combination with antimicrobial treatments. RT-qPCR was used to quantify bacteriocin gene expression by C. maltaromaticum UAL307 in vitro and on vacuum-packaged beef at 4°C and 10°C. Bacteriocin gene expression was highest at 10°C in vitro, and gene expression was higher in vitro than on meat. Carnocyclin A was the bacteriocin most consistently detected on meat. Phenolic acids were tested as outer membrane permeants to sensitize E. coli to bacteriocins produced by gram-positive bacteria. Syringic acid acted synergistically with C. maltaromaticum UAL307 cell-free culture supernatant to inhibit growth of E. coli in vitro. Green and red fluorescent proteins were evaluated as tools for monitoring bacterial viability and showed potential for use as intracellular pH probes for bacterial cells on meat.

• Subjects / Keywords

  • Heat-resistant Escherichia coli
  • Phenolic acids
  • Carnobaterium maltaromaticum
  • Bacteriocins
  • Fluorescent proteins
  • Minimum inhibitory concentration
  • Protective culture

• Graduation date

  Spring 2012

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3M31V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.