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Genes that are Affected in High Hydrostatic Pressure Treatments in a Listeria Monocytogenes Scott A ctsR Deletion Mutant

Liu, Yanhong, Huang, Lihan, Joerger, Rolf D., Gunther IV, Nereus W.
ARS USDA Submissions 2012 v.4 no.2 pp. 50
DNA, Listeria monocytogenes, RNA, adaptation, amino acids, bacterial proteins, biosynthesis, cell membranes, energy metabolism, fluorescent dyes, food contamination, food pathogens, food processing, foods, gene deletion, gene expression, gene induction, genes, heat stress, high pressure treatment, labeling techniques, microarray technology, mutants, nucleic acid hybridization, nucleosides, pathogen survival, protein synthesis, public health, purines, pyrimidines, resistance mechanisms, reverse transcriptase polymerase chain reaction, stress tolerance, transcription factors
Listeria monocytogenes is a food-borne pathogen of significant threat to public health. High Hydrostatic Pressure (HHP) treatment can be used to control L. monocytogenes in food. The CtsR (class three stress gene repressor) protein negatively regulates the expression of class III heat shock genes. A spontaneous pressure-tolerant ctsR L. monocytogenes deletion mutant 2-1 that was able to survive under HHP treatment was identified; however, there is only limited information about the mechanisms of survival and adaptation of this mutant in response to high pressure. Microarray technology was used to monitor the gene expression profiles of ctsR mutant 2-1 under pressure treatments. Total RNA was isolated from pressure-treated L. monocytogenes Scott A (450 Mpa, 3 min) ctsR mutant 2-1, labeled with fluorescent dyes, and hybridized to commercial oligonucleotide (35-mers) microarray chips representing the whole genome of L. monocytogenes. The gene expression changes determined by microarray assays were confirmed by real-time RT-PCR analyses. Compared to non-pressure-treated ctsR mutant 2-1, 14 genes were induced (> 2-fold increase) in the ctsR deletion mutant whereas 32 genes were inhibited (< -2-fold decrease). The induced genes included genes encoding proteins involved in synthesis of purines, pyrimidines, nucleosides, and nucleotides, transport and binding, transcription, cell membrane, DNA and energy metabolism, protein synthesis, and unknown functions. The inhibited genes included genes encoding proteins for transport and binding, cell envelope, transcription, amino acid biosynthesis, regulatory functions, cellular processes and central intermediary metabolism. This study enhances our understanding of how L. monocytogenes survives HHP and may contribute to the design of safe, accurate, and economically feasible HHP treatments for food processing.