Abstract
The aim of the present study was to assess the transcription of Listeria monocytogenes key virulence genes, namely sigB, prfA, hly, plcA, plcB, inlA, inlB, inlC and inlJ during subsistence on the surface of tomato, cucumber and carrot stored at 4, 10 and 30 °C for 0, 0.5, 6 and 24 h. Gene relative transcription was assessed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results obtained, indicated that the relative transcription of plcA, plcB and inlB was more affected during subsistence on cucumber surface whereas the relative transcription of sigB, prfA, hly, inlA and inlC was more affected on tomato surface. Subsistence of the pathogen on carrot surface had only marginal effect on the relative transcription of the virulence genes assessed in the present study. In the majority of the cases, the aforementioned effects were dependent on the storage temperature employed.
Highlights
Listeria monocytogenes is the etiological agent of foodborne listeriosis, the latest reports on which mention in the United States of America a total of 32 illnesses, 31 hospitalizations and 3 deaths (2017 annual report available at https://www.cdc.gov/fdoss/annual-reports/ index.html) and in the EU a total of 2621 confirmed cases, 1339 hospitalizations and 300 deaths (2019 annual report available at https://www.efsa.europa. eu/en/efsajournal/pub/6406)
The aim of the present study was to provide information regarding the transcriptional response of L. monocytogenes during subsistence on the surface of tomato, cucumber and carrot, stored at 4, 10 and 30 ◦C
Increase of the L. monocytogenes population was only observed during incubation of Brain Heart Infusion (BHI) broth at 10 and 30 ◦C as well as during incubation of cucumber at 30 ◦C
Summary
Listeria monocytogenes is the etiological agent of foodborne listeriosis, the latest reports on which mention in the United States of America a total of 32 illnesses, 31 hospitalizations and 3 deaths (2017 annual report available at https://www.cdc.gov/fdoss/annual-reports/ index.html (accessed on 20 May 2021)) and in the EU a total of 2621 confirmed cases, 1339 hospitalizations and 300 deaths (2019 annual report available at https://www.efsa.europa. eu/en/efsajournal/pub/6406 (accessed on 20 May 2021)). The virulence potential of this foodborne pathogen relies on the ability to cross the intestinal epithelial cells, escape from host defensive responses and disseminate through lymph and blood [1]. This infection requires the coordinated expression of a series of genes, including hly, plcA, plcB, inlA, inlB, inlC and inlJ. The alternative sigma factor B is encoded by sigB and has a key role in L. monocytogenes survival in nature and in the gastrointestinal tract It controls the transcription of more than 200 genes, affecting substantially L. monocytogenes responses to environmental stimuli and virulence [6]. It possesses a key role in directing cellular homeostasis and fine-tuning the virulence machinery of L. monocytogenes [7]
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