Technical Abstract Search Details

Technical Abstract Details


Title 174-05 Inhibition and Inactivation of <i>Listeria Monocytogenes</i> and <i>Escherichia Coli</i> O157:H7 Biofilms by Selenium
Presenter Meera Surendran Nair, Abhinav Upadhyay, Indu Upadhyaya, Anup Kollanoor - Johny, Kumar Venkitanarayanan, University of Connecticut, Storrs, CT
Abstract <i>Listeria monocytogenes</i> (LM) and <i>Escherichia coli</i> O157:H7 (EHEC) are major foodborne pathogens capable of forming biofilms, thereby serving as a source of food contamination in food processing plants. Therefore controlling these biofilms is critical for improving food safety. This study investigated the efficacy of Selenium (Se), a dietary essential mineral, in inhibiting LM and EHEC biofilm formation on polystyrene plates at 25&#176;C. Additionally, the effect of Se on surface attachment of planktonic cells and exo-polysaccharide (EPS) synthesis was studied. Moreover, the efficacy of Se in combination with hot water for rapidly inactivating fully formed LM and EHEC biofilms was determined. For the inhibition assay, polystyrene plates inoculated separately with LM (Scott A) or EHEC (ATCC 43895) (&#8764;6.0 log CFU/well) were treated with sub-inhibitory concentrations of Se (LM: 0.56 mM; EHEC: 28 mM), and incubated at 25&#176;C. The bacterial population in the biofilm was enumerated every 24 h for 96 h. Initial planktonic cell attachment and EPS production were determined using solid surface assay and ruthenium red staining assay. The inactivation of mature LM and EHEC biofilms was studied by treating pre-formed biofilms with the bactericidal concentration of Se (LM: 346 mM; EHEC: 462 mM) in combination with hot water (70 or 80&#176;C) for 0, 2, and 5 min. The study was replicated twice with duplicate samples for each treatment and control. Selenium reduced early attachment of planktonic cells, biofilm formation and EPS synthesis in both pathogens (P<0.05). Se in combination with hot water reduced biofilm-associated bacterial counts to undetectable levels at 5 min compared to control (P< 0.05). However, hot water treatment (70 and 80&#176;C) decreased biofilm-associated bacterial counts only by 1.0 log CFU/ml. The results suggest that Se could potentially be incorporated on food contact surfaces in processing plants for controlling LM and EHEC biofilms.
Year/Location2014 IFT Annual Meeting, June 21 – 24, 2014, New Orleans, LA
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