Antimicrobial and Fermentation Potential of Himanthalia elongata in Food Applications

Francesco Martelli; Claudia Favari; Pedro Mena; Stefano Guazzetti; Annalisa Ricci; Daniele Del Rio; Camilla Lazzi; Erasmo Neviani; Valentina Bernini

doi:10.3390/microorganisms8020248

Antimicrobial and Fermentation Potential of Himanthalia elongata in Food Applications

Microorganisms. 2020 Feb 13;8(2):248. doi: 10.3390/microorganisms8020248.

Authors

Affiliations

¹ Department of Food and Drug, University of Parma, Parco Area delle Scienze 49/A, 43124 Parma, Italy.
² Human Nutrition Unit, Department of Veterinary Science, University of Parma, Via Volturno, 39, 43125 Parma, Italy.
³ AUSL Reggio Emilia, Via Giovanni Amendola 2, 42122 Reggio Emilia, Italy.
⁴ School of Advanced Studies on Food and Nutrition, University of Parma, 43121 Parma, Italy.

Abstract

Himanthalia elongata is a brown oceanic seaweed rich in bioactive compounds. It could play an important role in food production because of its antimicrobial and antioxidant properties. Three strains belonging to the Lactobacillus casei group (Lactobacillus casei, Lactobacillus paracasei, and Lactobacillus rhamnosus) and a Bacillus subtilis strain were used for the solid-state fermentation of commercial seaweeds, and bacterial growth was monitored using the plate count method. High-pressure processing (HPP) was also employed (6000 bar, 5 min, 5 °C) before extraction. The antimicrobial activity of the extracts was tested in terms of the main food pathogenic bacteria (Salmonella spp., Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Bacillus cereus), and the phenolic content was estimated using the Folin-Ciocalteau method. In addition, targeted UHPLC-MS² methods were used to unravel the profile of phlorotannins. H. elongata allowed the growth of the L. casei group strains and B. subtilis, showing the fermentability of this substrate. Significant antimicrobial activity toward L. monocytogenes was observed in the extracts obtained from unfermented samples, but neither fermentation nor HPP enhanced the natural antimicrobial activity of this seaweed species. The content in the phenolic compounds decreased because of the fermentation process, and the amount of phenolics in both the unfermented and fermented H. elongata extracts was very low. Despite phlorotannins being related to the natural antimicrobial activity of this brown seaweed, these results did not support this association. Even if fermentation and HPP were not proven to be effective tools for enhancing the useful compounds of H. elongata, the seaweed was shown to be a suitable substrate for L. casei group strains as well as for B. subtilis growth, and its extracts exhibited antimicrobial activity toward foodborne pathogens.

Keywords: Himanthalia elongata; antimicrobial activity; fermentation; food safety; foodborne pathogens; phlorotannins; seaweeds.