Solar irradiance limits the long ‐term survival of Listeria monocytogenes in seawater

In this study we investigated the possibility that this pathogen could survive in seawater for an extended time period. Freshly collected seawater samples were inoculated with 1 × 108 CFU per ml of L. monocytogenes EGD‐e and survival was monitored by plate counting for up to 25 days. When incubated in the dark, either at ambient temperatures (4–14°C) or at 16°C, >104 CFU per ml survivors were present after 25 days. However, when the seawater cell suspensions were exposed to ambient light (solar irradiation) and temperatures, L. monocytogenes lost viability rapidly and no survivors could be detected after the 80 h time point. Both UV‐A and visible light in the blue region of the spectrum (470 nm) were found to contribute to this effect. The stress inducible sigma factor σB was found to play a role in survival of L. monocytogenes in seawater. Together these data demonstrate that solar irradiation is a critical determinant of L. monocytogenes survival in marine environments. The data further suggest the possibility of controlling this food‐borne pathogen in food‐processing environments using visible light. Significance and Impact of the StudyListeria monocytogenes is a food‐borne bacterial pathogen capable of causing the life‐threatening infection, listeriosis. In seafood the route of contamination from the environment is often not well understood as this pathogen is not generally thought to survive well in seawater. Here we provide evidence that L. ...
Source: Letters in Applied Microbiology - Category: Microbiology Authors: Tags: Original Article Source Type: research