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United States Department of Agriculture

Agricultural Research Service

Title: Mutations in Crp/fnr Family of Regulatory Genes in Listeria Monocytogenes Do Not Alter the Heat Resistance of the Pathogen

item Bayles, Darrell
item Uhlich, Gaylen

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 9, 2005
Publication Date: August 14, 2005
Citation: Bayles, D.O., Uhlich, G.A. 2005. Mutations in crp/fnr family of regulatory genes in listeria monocytogenes do not alter the heat resistance of the pathogen. Meeting Abstract. Poster P1-11. pg. 69.

Technical Abstract: The availability of whole genome sequencing data for Listeria monocytogenes has created opportunities for exploring the role that unique genomic features have in food safety and pathogenesis. A surprising feature of the L. monocytogenes genome is the presence of 15 regulatory genes in the Crp/Fnr family. By comparison, Escherichia coli has two regulators in this family and Bacillus subtilis has one. We constructed single transposon mutants for 12 of the 15 L. monocytogenes Crp/Fnr regulators using site specific recombination. Since the gene networks controlled by these regulators is currently undetermined, each of the 12 Crp/Fnr mutants and the wild type strain were heat challenged at 60C using an immersed-coil heating apparatus to determine if these L. monocytogenes Crp/Fnr mutants demonstrated altered heat tolerance. All the test strains of L. monocytogenes were independently grown to stationary phase in brain heart infusion broth and were heat challenged in four separate trials. The thermal inactivation curves were modeled to calculate the underlying mean and mode of the heat resistance distribution for each mutant strain, and each mutant strain was compared to the wild type strain using Dunnett's test to adjust for the multiple comparisons. All the Crp/Fnr mutant strains tested had heat resistance characteristics similar to the wild type strain (adjusted P > 0.05) indicating that mutations in these Crp/Fnr genes neither increased nor decreased the sensitivity of L. monocytogenes to mild heat. Additional tests are underway to further elucidate the regulatory role of these L. monocytogenes Crp/Fnr genes.

Last Modified: 4/22/2015
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