Insertional mutagenesis of Listeria monocytogenes 568 reveals genes that contribute to enhanced thermotolerance.
The objectives of this study were to identify molecular mechanisms of thermotolerance using transposon mutants of Listeria monocytogenes 568, serotype 1/2a, and to compare their thermal death kinetics at 52, 56 and 60 degrees C. Sixteen Tn917 transposon mutants with enhanced heat resistance were acquired from a library of 4300 mutants following a multi-step screening process. Genetic regions with Tn917 insertions encompassed a broad range of functionalities including; transport, metabolism, replication and repair, general stress, and structural properties. Modeling of the heat inactivation data using the Geeraerd et al. and Whiting (Fermi) models showed that the mutants' enhanced thermal resistance was manifested mostly through a significant (p<or=0.05) extension of the lag period on the thermal death curve. This new knowledge impacts our understanding of molecular mechanisms affecting the kinetics of thermally induced cell death and enables the development of safer thermal processes.
Ells
Timothy C
TC
Agriculture and Agri-Food Canada, Atlantic Food and Horticulture Research Centre, Kentville, NS, Canada.
Speers
R Alex
RA
Hansen
Lisbeth Truelstrup
LT
D004251:DNA Transposable Elements / Q000235:genetics; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D015723:Gene Library; D005798:Genes, Bacterial / Q000235:genetics*; D006358:Hot Temperature; D008089:Listeria monocytogenes / Q000235:genetics / Q000502:physiology*; D016254:Mutagenesis, Insertional; D009154:Mutation / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics; D013997:Time Factors
D004251:DNA Transposable Elements