Inactivation of the Crp/Fnr family of regulatory genes in Listeria monocytogenes strain F2365 does not alter its heat resistance at 60 degrees C.
A surprising facet of the Listeria monocytogenes genome is the presence of 15 genes that code for regulators in the Crp/ Fnr family and include the virulence regulator PrfA. The genes under the transcriptional control of these regulators are currently undetermined, with the exception of some genes controlled by the major virulence regulator PrfA. Using 12 strains of L. monocytogenes, each with an inserted gene cassette that interrupts and renders nonfunctional a different L. monocytogenes strain F2365 Crp/Fnr regulator, we heat challenged each strain at 60 degrees C with an immersed-coil heating apparatus, modeled the survivor data to calculate the underlying mean and mode of the heat resistance distribution for each strain, and compared the thermal tolerance of each mutant to the wild-type strain to determine if any of the Crp/Fnr mutants demonstrated altered heat tolerance. All 12 of the Crp/Fnr mutant strains tested had heat resistance characteristics similar to the wild-type strain (P > 0.05), indicating that mutations in these Crp/Fnr genes neither increased nor decreased the sensitivity of L. monocytogenes strain F2365 to mild heat.
Bayles
Darrell O
DO
Microbial Food Safety Research Unit, Eastern Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA. dbayles@errc.ars.usda.gov
Uhlich
Gaylen A
GA
D001426:Bacterial Proteins / Q000235:genetics*; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006358:Hot Temperature; D008089:Listeria monocytogenes / Q000235:genetics* / Q000254:growth & development; D014158:Transcription, Genetic
D001426:Bacterial Proteins