Effect of high pressure on the antimicrobial activity and secondary structure of the bacteriocin nisin

• Published in: Innovative food science & emerging technologies 2018-06, Vol.47, p.9-15
• Main Authors: Modugno, Chloé, Loupiac, Camille, Bernard, Antoine, Jossier, Audrey, Neiers, Fabrice, Perrier-Cornet, Jean-Marie, Simonin, Hélène
• Format: Article
• Language: English
• Subjects: Activity; Food engineering; High pressure; Life Sciences; Nisin; Secondary structure
• ISSN: 1466-8564; 1878-5522
• DOI: 10.1016/j.ifset.2018.01.006

Effect of high pressure (HP) treatment on the antimicrobial properties and the structure of nisin was evaluated. Nisin solutions at pH 2.8 or 6.1 were treated by HP at 500 MPa – 10 min – 20 °C and their antimicrobial potency was determined. It appeared that HP clearly impacted the antimicrobial activity of nisin, with respective activity loss of 22.5% and 49.9% at pH 2.8 and 6.1. Structural analysis of nisin by circular dichroism and Fourier transform-infrared spectroscopies revealed that the decrease of nisin antimicrobial activity was likely due to the unfolding of the protein induced by HP. A loss of nisin β-turns structure, particularly significant at neutral pH, was linked to the drastic drop in antimicrobial activity, as these structures are implicated in the nisin interaction with the bacterial membrane. The combination of nisin and high pressure (HP) can be use at an industrial scale to inactivate bacteria. Nisin is allowed as a food additive (E234) and can be added at a final concentration ranging from 120 to 500 IU/g, depending on the product. In this work, we showed that HP can induce a significant reduction of nisin activity (-22.5% at pH 2.8 and -49.9% at pH 6.1). Therefore, this activity loss could be taken into account to manage the final nisin concentration in HP-treated food products. •HP treatment (500 MPa – 10 min – 20 °C) reduced the antimicrobial activity of nisin of 22.5% at pH 2.8 and 49.9% at pH 6.1.•While nisin is randomly coiled at pH 2.8, the presence of β-turns at pH 6.1 induced a lower stability to HP.•The drop in antimicrobial activity after HP was due to the unfolding of nisin, resulting in a loss of the β-turns structure.