The protein landscape of Listeria monocytogenes ScottA within its supraoptimal temperature growth range reveals a weakness to oxidative stress

Listeria monocytogenes is problematic to public health and food industries due to listeriosis and its transmission via contaminated food. Dealing with L. monocytogenes typically involves hurdle technologies to minimise risk. Simple approaches that could be applied within food production environments and during food processing that further eliminates or controls L. monocytogenes would be ideal. Since temperature essentially governs rates of inactivation we used shotgun proteomics of strain ScottA to try to discern weaknesses that could be exploited in situations where mild heat (< 50°C) is applied during food processing or during sanitation. For this purpose the proteomes of lineage I strain ScottA were determined throughout its supraoptimal temperature growth range (37-45°C) and at a non-growth permissive temperature of 50°C. Tryptic peptides were identified in extracts using label free LC/tandem MS-MS with filtered spectral counts analysed by multivariate statistics to detect significant changes in protein abundances. Results demonstrate that while protein turnover and chaperones dramatically collapse when temperature attains non-permissiveness, oxidative stress management as well as DNA replication, RNA polymerase, and tRNA charging collapse in the range of 42-45°C. This inherent thermally induced weakness may provide the means to better optimise decontamination strategies and processing steps in industrial scale operations.