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Biofilm Formation of Listeria SP and Alicyclobacillus SP in Pure and Mixed Cultures


<OL> <LI> The identification and characterization of the interrupted gene sequences within Listeria innocua reduced surface growth mutants. <LI> The isolation and identification of bacteria within an undefined mixed strain biofilm and re-formulation of bacteria within the floor drain biofilm for the the competitive exclusion of L. monocytogenes. <LI> The characterization of the ability of Alicyclobacillus acidoterrestris to form biofilms.

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Non-Technical Summary: Biofilms growing within processing plants can be a source of pathogenic and spoilage bacteria in foods. Knowledge of the genetics, growth within mixed systems and the influence of spore formation during the biofilm growth cycle can be applied to cleaning and sanitation of the food environment to produce safer foods with longer shelf-life. <P> Approach: This project will focus upon biofilm production of Listeria sp. and Alicyclobacillus sp. Listeria monocytogenes a human pathogen that known for its ability persist in biofilms within the food processing environment and the first two objectives deal with this organism. The third objective deals with Alicyclobacillus,a major spoilage organism in juice processing, however its ability to form biofilms has yet to be characterized. The first objective of the project is to identify and characterize the interrupted gene sequences from mutants of Listeria innocua with reduced biofilm forming ability using arbitrary PCR and ligation-mediated PCR (LMPCR). After identification of interrupted sequences, complementation experiments will be performed. Research on basic science behind biofilm production of Listeria sp may yield the basis for new biofilm control strategies. The second objective of this project is to isolate and identify bacteria within an undefined mixed strain biofilm. These organisms will be used to establish a defined strain mixed biofilm for the competitive exclusion of L. monocytogenes in a floor drain biofilm system. Competitive exclusion may be an approach that could be useful in control of Listeria monocytogenes within the food industry. The third objective will be to screen Alicyclobacillus strains for their ability to form biofilms under a variety of conditions (32, 37, 43 and 55C and three bacteriological media). After identifying optimal conditions, biofilms will be grown in a drip flow reactor and formation of vegetative cells and spores will be monitored. The involvement of spores within the Alicyclobacillus biofilm life cycle will evaluated and the structure of the spores be studied using atomic force and electron microscopy. Understanding the surface growth of Alicyclobacillus acidoterrestris may allow the juice processing industry to modify cleaning and sanitation to allow better control of this spoilage organism.

McLandsborough, Lynne
University of Massachusetts - Amherst
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