MOLECULAR MICROBIOLOGY AND CONTROL OF ENTERIC PATHOGENS THAT CONTAMINATE FRESH PRODUCE
Location: Produce Safety and Microbiology Research
Title: ROLE OF UVRA IN THE GROWTH AND SURVIVAL OF LISTERIA MONOCYTOGENES UNDER UV IRRADIATION AND ACID AND BILE STRESS
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 3, 2006
Publication Date: December 2, 2006
Citation: Kim, S., Gorski, L.A., Reynolds, J.O., Orozco, E., Fields, S., Park, Y., Boruki, M.K. 2006. Role of uvra in the growth and survival of listeria monocytogenes under uv irradiation and acid and bile stress. Journal of Food Protection. 69:3031-3036
Interpretive Summary: The uvrA gene of Listeria monocytogenes was deleted. This gene, in other bacteria, controls the response to UV irradiation by aiding in the repair of damaged DNA. The uvrA mutant was tested to see how it survived UV irradiation as well as other stresses that might damage DNA, and would be seen by L. monocytogenes when it was involved in creating disease in the host—namely acid stress and bile stress. The uvrA mutant was very sensitive to UV irradiation, growth in acidic medium was slightly impaired, and growth in the presence of bile salts was impaired. These results suggest that uvrA is needed for optimal growth and survival of L. monocytogenes in various environmental stresses.
Listeria monocytogenes encounters numerous stresses both in the food environment and during infection of the host. The ability to survive and tolerate low pH and bile, which are two major stresses, is of particular importance for survival within the host. uvrA has been shown to be involved in the repair of acid-induced DNA damage and adaptation to low pH in other bacteria. Thus, a uvrA gene in-frame deletion mutant was constructed to identify the role of uvrA in the growth and survival of L. monocytogenes in various environmental conditions. The uvrA mutant was highly sensitive to UV irradiation. Growth under normal laboratory conditions was impaired during exponential phase and the time to reach the exponential phase growth, TVmax, was significantly delayed (P < 0.05). Growth of the uvrA mutant in acidic medium (pH 5) was slightly impaired and the TVmax was significantly delayed (P < 0.05). Growth and the TVmax of the mutant in the presence of 0.3% bile salts were also significantly impaired (P < 0.05). These results suggest that uvrA is needed for optimal growth and survival of L. monocytogenes in various environmental stresses.