Title: Gene expression profiling of Listeria monocytogenes strain F2365 in UHT pasteurized skim milk Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 5, 2008
Publication Date: August 3, 2008
Citation: Liu, Y. 2008. Gene expression profiling of Listeria monocytogenes strain F2365 in UHT pasteurized skim milk. Meeting Abstract. P23. Technical Abstract: Introduction: Listeria monocytogenes is a food-borne pathogen of significant threat to public health. L. monocytogenes has the ability to grow or survive at refrigeration temperatures and under conditions of relatively low pH, high salt and low water activity in foods. However, the factors contributing to the survival and growth of such strains in food remain unclear. Purpose: Monitor the gene expression profiles of L. monocytogenes strain F2365 in UHT pasteurized skim milk using microarray technology. Methods: Total RNA was isolated from strain F2365 in UHT pasteurized skim milk after 24 hours at 4 degree C, and labeled with fluorescent dyes, and hybridized to custom-made oligonucleotide (35-mers) microarray chips containing the whole genome of the serotype 4b strain F2365 of L. monocytogenes. Results: Compared to L. monocytogenes grown in brain heart infusion broth (BHI) for 24 hours at 4 degree C, 26 genes were up-regulated (> 2-fold) in UHT pasteurized skim milk, whereas 14 genes were down-regulated (< -2-fold). The up-regulated genes included genes encoding for transport and binding, transcriptional regulators, proteins in amino acid biosynthesis and energy metabolism, protein synthesis, toxin production and resistance, cell division, and hypothetical proteins. The down-regulated genes included genes that encode for transport and binding, protein synthesis, cellular processes, cell envelope, energy metabolism, and a transcriptional regulator and an unknown protein. The gene expression changes determined by microarray assays were confirmed by real-time RT-PCR analyses. Furthermore, cells of L. monocytogenes in skim milk displayed the same sensitivity to oxidative stress as cells grown in BHI, demonstrating that the elevated levels of genes encoding for manganese transporter complexes in milk did not result in changes in oxidative stress sensitivity. Significance: This study represents the first report on global transcriptional gene expression profiling of L. monocytogenes in a liquid food.