Title: Construction of Listeria monocytogenes mutants with in-frame deletions in putative ATP-binding cassette (ABC) transporters and analysis of their growth under stress conditions Authors
|Ceruso, Marina -|
|Pepe, Tiziana -|
|Cortesi, Maria Luisa -|
Submitted to: Journal of Microbial and Biochemical Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 22, 2012
Publication Date: December 20, 2012
Citation: Liu, Y., Ceruso, M., Pepe, T., Cortesi, M., Gunther, N.W., Fratamico, P.M. 2012. Construction of Listeria monocytogenes mutants with in-frame deletions in putative ATP-binding cassette (ABC) transporters and analysis of their growth under stress conditions. Journal of Microbial and Biochemical Technology. 4(7):141-146. Interpretive Summary: The bacterium, Listeria monocytogenes, is an important food-borne pathogen that causes disease in humans and animals. L. monocytogenes is difficult to eliminate since it can form a biofilm (a complex aggregation of microorganisms growing on a solid substrate). Proteins known as ATP-binding cassette (ABC) transporters are responsible for nutrient uptake and biofilm formation in L. monocytogenes. To understand how these transporters behave under different food-related stress conditions, genes that encode for one of the ABC transporters were deleted from the bacterial genome forming what are referred to as mutant strains. The growth of these mutant strains was tested under different stress conditions and in different food. Our results showed that these mutant strains grew differently under different stress conditions. In addition, one of the mutant strains showed increased capacity for biofilm formation. Information from this study enhances the understanding of the role of ABC transporters in L. monocytogenes under stress conditions and provides information to help in the development intervention strategies.
Technical Abstract: Listeria monocytogenes is a foodborne pathogen that is difficult to eliminate since it can survive under multiple stress conditions such as low pH and low temperature. Understanding its survival under stress conditions is important to control this pathogen in food. ABC transporters have been shown to be induced in L. monocytogenes in food subjected to high pressure and nisin treatments; therefore, we hypothesized that these genes are involved in general stress responses. To study the function of these genes, deletion mutants of ABC transporters genes (LMOf236_1875, LMOf2365_1877) in L. monocytogenes F2365 were created. These mutants were tested under different stress conditions and in different foods (milk and apple juice). Compared to the wild type, both mutants showed slow growth under nisin, salt, and acid treatments. However, in milk and apple juice, the growth rates of both mutants were the same compared to the wild type. Moreover, the deletion mutant LMOf2365_1877 had an increased capacity to form biofilms compared to the wild type. Our results indicate that these deletion mutants were more sensitive to multiple stress conditions compared to the wild type, indicating that these genes many contribute to the general stress response in L. monocytogenes. Analyzing the growth of these mutants under multiple stress conditions may help develop intervention strategies to control L. monocytogenes in food.