Cold plasma inactivation of internalised bacteria and biofilms for Salmonella enterica serovar Typhimurium, Listeria monocytogenes and Escherichia coli

Abstract

Microbial biofilms and bacteria internalised in produce tissue may reduce the effectiveness of decontamination methods. In this study, the inactivation efficacy of in-package atmospheric cold plasma (ACP) afterglow was investigated against Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli in the forms of planktonic cultures, biofilms formed on lettuce and associated bacteria internalised in lettuce tissue. Prepared lettuce broth (3%) was inoculated with bacteria resulting in a final concentration of ~7.0 log 10 CFU/ml. For biofilm formation and internalisation, lettuce pieces (5 x 5 cm) were dip-inoculated in bacterial suspension of ~7.0 log 10 CFU/ml for 2 h and further incubated for 0, 24 and 48 h at either 4°C or room temperature (~22°C) in combination with light/dark photoperiod or at 4°C under dark conditions. Inoculated samples were sealed inside a rigid polypropylene container and However, the existence of biofilms and internalised bacteria should be considered for further optimisation of ACP treatment parameters in order to achieve an effective control of the realistic challenges posed by foodborne pathogens.

Cold Plasma Inactivation of Escherichia coli O157:H7 Biofilms

“…In a study of pathogen biofilms grown directly on produce, lettuce leaves were dip-inoculated in cultures of Salmonella Typhimurium, L. monocytogenes or E. coli, and incubated for up to 48 h to allow biofilms to form (Ziuzina et al, 2015). These were then packaged and treated with quenched cold plasma.…”

“…Typically, high voltage electricity is used to ionize gas molecules into a reactive plasma, which can inactivate pathogenic bacteria and viruses (Bermúdez-Aguirre et al, 2013;Lacombe et al, 2017;Min et al, 2017). Cold plasma has also shown specific activity against biofilms, including biofilm-associated Salmonella, Listeria monocytogenes and E. coli biofilms (Brelles-Mariño, 2012;Niemira et al, 2014;Ziuzina et al, 2015). One challenge for cold plasma as an antimicrobial process can be the treatment times required for inactivation, which can vary significantly with the type of cold plasma technology being used.…”

Essential Oils-Based Antibacterial Agent Against Escherichia coli O157:H7 Biofilm on Cucumber

“…After disinfecting, cucumber peel pieces were submerged in cell suspensions with a concentration of ∼10 5 CFU mL −1 , and incubated at 4C overnight to facilitate cell attachment (Ziuzina et al . ). After incubation, pieces were rinsed to remove unattached cells, and dried naturally.…”

Evaluation of plasma, high‐pressure and ultrasound processing on the stability of fructooligosaccharides

“…As reported by Ziuzina et al . (), complete bacterial inactivation was achieved after 20 s of direct exposure and 45 s of indirect exposure.…”