title: A Bioengineered Nisin Derivative, M21A, in Combination with Food Grade Additives Eradicates Biofilms ofListeria monocytogenes.
abstract: The burden of foodborne disease has large economic and social consequences worldwide. Despite strict regulations, a number of pathogens persist within the food environment, which is greatly contributed to by a build-up of resistance mechanisms and also through the formation of biofilms. Biofilms have been shown to be highly resistant to a number of antimicrobials and can be extremely difficult to remove once they are established. In parallel, the growing concern of consumers regarding the use of chemically derived antimicrobials within food has led to a drive toward more natural products. As a consequence, the use of naturally derived antimicrobials has become of particular interest. In this study we investigated the efficacy of nisin A and its bioengineered derivative M21A in combination with food grade additives to treat biofilms of a representative foodborne disease isolate ofListeria monocytogenes. Investigations revealed the enhanced antimicrobial effects, in liquid culture, of M21A in combination with citric acid or cinnamaldehyde over its wild type nisin A counterpart. Subsequently, an investigation was conducted into the effects of these combinations on an established biofilm of the same strain. Nisin M21A (0.1 μg/ml) alone or in combination with cinnamaldehyde (35 μg/ml) or citric acid (175 μg/ml) performed significantly better than combinations involving nisin A. All combinations of M21A with either citric acid or cinnamaldehyde eradicated theL. monocytogenesbiofilm (in relation to a non-biofilm control). We conclude that M21A in combination with available food additives could further enhance the antimicrobial treatment of biofilms within the food industry, simply by substituting nisin A with M21A in current commercial products such as Nisaplin®(Danisco, DuPont).
authors.affiliation: APC Microbiome Institute, School of Microbiology, University College Cork Cork, Ireland.
authors.forename: Muireann K
authors.initials: MK
authors.lastname: Smith
authors.affiliation: APC Microbiome Institute, School of Microbiology, University College Cork Cork, Ireland.
authors.forename: Lorraine A
authors.initials: LA
authors.lastname: Draper
authors.affiliation: Wageningen University & Research Wageningen, Netherlands.
authors.forename: Pieter-Jan
authors.initials: PJ
authors.lastname: Hazelhoff
authors.affiliation: APC Microbiome Institute, School of Microbiology, University College CorkCork, Ireland; Teagasc Food Research CentreCork, Ireland.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Cotter
authors.affiliation: APC Microbiome Institute, School of Microbiology, University College Cork Cork, Ireland.
authors.forename: R P
authors.initials: RP
authors.lastname: Ross
authors.affiliation: APC Microbiome Institute, School of Microbiology, University College Cork Cork, Ireland.
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
keywords: Listeria monocytogenes; bioengineered; biofilm; cinnamaldehyde; citric acid; combinations; nisin