The phage shock protein response of Listeria monocytogenes influences tolerance to the multipeptide bacteriocin garvicin KS

Summary

Food waste due to perishable and unsafe food products is a major issue worldwide. For some high-quality perishable food products, such as fresh fish and cold-smoked salmon, traditional food preservation techniques are unsuitable as they can compromise sensory qualities such as flavor, texture, and freshness. These products often support the growth of the human pathogen Listeria monocytogenes, which can be present if thermal treatment is not applied. Thus, antilisterial bacteriocins, such as garvicin KS (GarKS), in combination with other technologies like high-pressure processing, are being investigated as hurdle strategies to increase the shelf life and food safety of fish products. In this study, we aimed to identify potential resistance development and genetic factors affecting the susceptibility of L. monocytogenes towards GarKS. We show that L. monocytogenes strains associated with fish products and fish processing plants are susceptible to GarKS with MIC values ranging from 20 to 275 nM. By RNA sequencing, we showed that exposure to GarKS resulted in an upregulation of genes involved in the phage shock protein (psp) response. Furthermore, isolation of resistant mutants indicated a low frequency of resistance to GarKS (10⁻9 to 10⁻11). The GarKS-tolerant mutants isolated (2-fold increased MIC values) were shown to harbor disruption mutations in lmo2468, encoding a PspC-domain-containing protein. Overexpression of this gene increased susceptibility to GarKS two-fold and restored wild-type susceptibility in a disruption mutant. This study thus demonstrates that resistance development to GarKS is rare and identifies the phage shock protein response as a key player involved in susceptibility to GarKS.

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DOI : doi.org/10.1007/s00253-025-136...
NVA : hdl.handle.net/11250/5364215