Determination of genes involved in heat resistance response of Cronobacter sakazakii

Abstract

Cronobacter sakazakii is considered an emerging opportunistic pathogen causing meningitis, septicaemia and enterocilitis in neonates, related to the use of contaminated Powdered Infant Formula (PIF). C. sakazakii has an unusual surviving ability under dry conditions and has been suggested to be one of the most thermotolerant members of the Enterobacteriaceae. It is necessary to understand the molecular mechanisms underlying the thermal resistance of C. sakazakii and may ultimately be useful in the development of control strategies in PIF factories. In the current study, a transposon mutagenesis approach was used to identify the genes involved in heat resistance. A total of 23 mutants were found corresponding to 12 different defective genes. Heat resist once of selected mutants were determined with the use of the thermoresistometer Mastia. Only 2 mutants had a greater sensitivity to heat compared with the heat resistance of the wild type. Genes identified to be involved in the cellular response to thermal treatments were Ribosome maturation protein RimP and Outer membrane Porin L (OmpL). The results suggest that the novo protein synthesis, and the use of cysteine for the formation of disulfide bonds for stabilization of proteins against denaturation during thermal treatments are key processes in the resistance against heat stress.