The purpose of the research has been to develop an experimental biofilm ecocystem for the characterization of Listeria monocytogenes biofilms in a simulated food processing (SFP) environment. Individual strains of L. monocytogenes were initially surveyed for their ability to attach to surfaces and form biofilms under a variety of conditions. Five strains of L. monocytogenes were then screened for optimal cell attachment and biofilm formation. Significant differences in surface attachment and biofilm formation were observed among the different strains of L. monocytogenes. The biofilms of the five-strain mixture of L. monocytogenes were formed on surfaces that are commonly used in food processing facilities, such as stainless steel and Teflon®. The biofilms were subjected to the SFP system in sequential 24-h daily cycles. Conditions of the SFP system included: starvation, washing, rinsing, and sanitation that routinely occur in a food processing plant. Cell survival in biofilms was determined during the time course of the experiment. The susceptibility of the cells in biofilms and detached cells to different sanitizers was measured. The morphology of the cells in biofilms and the planktonic cells detached from biofilms was observed. The study indicated that the progressive resistance developed by L. monocytogenes biofilms to a sanitizer could protect the cells in biofilms from this and other sanitizing agents. The progressive resistance and cross protection was observed in biofilms, but not in detached cells. These findings could provide a basis for further research on the mechanism of progressive resistance to stresses by L. monocytogenes in biofilms under food processing conditions. The data may help to establish effective sanitation programs for food processing and related industries.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-08252005-000030 |
| Date | 25 August 2005 |
| Creators | PAN, YOUWEN |
| Contributors | Fred Breidt, Sophia Kathariou, Hosni Hassan |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-08252005-000030/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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