Strain-level characterization of cold-stressed Listeria monocytogenes using maldi-tof mass fingerprinting.

Listeria monocytogenes, a common food borne bacterial pathogen, could survive in stress conditions applied in food production such as cold environments. Twenty-eight strains of L. monocytogenes under cold stress were subjected to MALDI-TOF MS analysis and compared with control strains under normal growth conditions. The resulting protein mass finger printings were visualized by phyloproteomic cluster and self-organized map (SOM). It was observed that after cold-stressed treatment, all strains exhibited change of mass finger printings. In most strains, the variations of the fingerprinting profiles were significant. The diversity in protein fingerprinting of L. monocytogenes after cold stress was also improved. The strain-level differentiation of the stressed L. monocytogenes would not only improve the understanding of bacterial responses to cold stress but also facilitate classification and detection of stressed bacteria in food industry. Practical applications Listeria monocytogenes that causes lethal listeriosis could survive in cold-stressed treatment and pose high risk to food safety. However, the entire picture of the physiology of stress response adaptation of this strain is still unknown. The protein fingerprinting analysis of the cold-stressed L. monocytogenes provided an entire picture of phenotypic stress response adaptation at strain level and helped to understand bacterial resistance to cold stress. Additionally, the study on the peptide fingerprints changes, covering 28 strains of L. monocytogenes from different sources would be particularly valuable for the strain-level differentiation and detection of stressed bacteria in food industry. [ABSTRACT FROM AUTHOR]