Source: UNIVERSITY OF ILLINOIS submitted to
VIRULENCE OF LISTERIA MONOCYTOGENES GROWN AS BIOFILMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0208643
Grant No.
(N/A)
Project No.
ILLU-698-383
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2006
Project End Date
Sep 30, 2010
Grant Year
(N/A)
Project Director
Martin, S. E.
Recipient Organization
UNIVERSITY OF ILLINOIS
2001 S. Lincoln Ave.
URBANA,IL 61801
Performing Department
FOOD SCIENCE & HUMAN NUTRITION
Non Technical Summary
Recent outbreaks of foodborne illness caused by consumption of Listeria monocytogenes contaminated, ready-to-eat meat and poultry products demonstrate the critical need to address this serious public health problem. Cells of L. monocytogenes can form biofilms on stainless steel surfaces of processing equipment and contaminate product as the product contacts the listerial biofilm. A biofilm is defined as a biologically active matrix of cells and extracellular substances produced by microorganisms. Virulence of L. monocytogenes cells grown as biofilms may differ from those grown in liquid culture. Little research has been performed to examine this critical question.
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
71250101100100%
Knowledge Area
712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins;

Subject Of Investigation
5010 - Food;

Field Of Science
1100 - Bacteriology;
Goals / Objectives
The objectives of this proposal are to examine biofilm formation by Listeria monocytogenes on stainless steel surfaces, and to compare the virulence of listerial cells grown in liquid culture and as a biofilm.
Project Methods
Cells of Listeria monocytogenes LCDC will be grown in liquid medium (tryptic soy broth) and in the same medium as a biofilm. The specific activities of listeriolysin O, phospholipase C, catalase and superoxide dismutase will be determined in cells grown free in liquid culture and as biofilms.

Progress 10/01/06 to 09/30/10

Outputs
OUTPUTS: Investigator left the University of Illinois in 2010. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Investigator left the University of Illinois in 2010.

Publications

  • No publications reported this period


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: The objectives of the current research are to determine if Listeria monocytogenes cells are more virulent when grown as biofilms than when grown in liquid culture (planktonic). We have shown that the activities of listeriolysin O, catalase and superoxide dismutase (virulence enzymes) are increased in listerial cells grown as biofilms. We are currently developing a microarray assay to measure the amount of messenger ribonucleic acid produced for these enzymes in biofilm and planktonic listerial cells. PARTICIPANTS: Vaishali Dharmarha - graduate student and Lina Dovilas - graduate student. TARGET AUDIENCES: Food manufactures and federal and state regulatory agencies. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
If cells of Listeria monocytogenes growing as biofilms are more virulent than planktonic cells, the implications for the food industry could be significant. Listeria monocytogenes grows in a biofilm on products like sliced luncheon meats, cheese and other food products. More virulent biofilm-grown listerial cells would be of greater health concern.

Publications

  • Dharmarha, V.B. 2008. Comparison of catalase, superoxide dismutase and listeriolysin O activities in planktonic and biofilm cells of Listeria monocytogenes. M.S., University of Illinois, Urbana, Illinois.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Specific activities of three virulence factors (catalase, superoxide dismutase, and listeriolysin O) were examined in Listeria monocytogenes strain 10403S grown as planktonic (free) cells in liquid suspension and grown as biofilm (attached) cells on stainless steel chips. Planktonic cells of L. monocytogenes strain 10403S were grown in tryptic soy broth for 12 hours to the early stationary phase. Biofilms were allowed to grow for five days at 37 degrees C with daily washing and addition of fresh growth medium. Significant differences in specific activities of catalase, superoxide dismutase, and listeriolysin O were observed when cells grown planktonically were compared to cells grown as biofilms. The specific activity of catalase was found to be 7-fold higher in biofilm cells than planktonic cells, while specific activities of superoxide dismutase and listeriolysin O were 6- and 29-fold greater in biofilm cells than planktonic cells, respectively. The results suggest that the biofilm phenotype resulted in differential expression of proteins than the planktonic phenotype and that biofilm growth of L. monocytogenes is not only a potential source of contamination in the food processing plant environment but the pathogen may also be more virulent and infectious than free L. monocytogenes cells. PARTICIPANTS: Vaishali Dharmarha - Graduate Student. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Results from this study suggest that when Listeria monocytogenes grows as a biofilm, the cells may be more virulent than when the cells grow planktonically.

Publications

  • Dharmarha, V. 2008. Comparison of catalase, superoxide dismutase and listeriolysin O specific activities in planktonic and biofilm cells of Listeria monocytogenes. M.S. thesis, University of Illinois.


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Cells of the foodborne pathogen Listeria monocytogenes were grown in liquid culture(planktonic)and as biofilms on stainless steel chips. The specific activities of three virulence enzymes (catalase, superoxide dismutase and listeriolysin O) were determined. For all three of the virulence enzymes examined, the specific activities were significantly higher in cells grown as biofilms compared to planktonic cells. These results suggest that when L. monocytogenes grows as a biofilm (on products like sliced poultry and hot dogs), the biofilm listerial cells may be more virulent than similar cells grown in liquid medium. PARTICIPANTS: Ms. Vaishali Dharmarha TARGET AUDIENCES: Food industry professionals, regulatory agencies, and food microbiologists.

Impacts
Results from this study demonstrate the importance of the elimination of Listeria monocytogenes from human food. When L. monocytogenes grows as a biofilm, it may be even more pathogenic than similar cells grown in liquid medium.

Publications

  • No publications reported this period