Antimicrobial and antibiofilm potentiation by a triple combination of dual biocides and a phytochemical with complementary activity. (May 2023)

• Record Type: Journal Article
• Authors: Fernandes, Susana; Gomes, Inês B.; Simões, Manuel
• Is Part Of: Food research international. Volume 167(2023)
• Publication Date: 2023-05
• Subjects: Benzalkonium chloride -- Biofilm control -- Checkerboard assay -- Curcumin -- Glycolic acid -- Glyoxal -- Peracetic acid -- 10-undecenoic acid; Food -- Analysis -- Periodicals; Food industry and trade -- Periodicals; Food industry and trade -- Canada -- Periodicals; Food Technology -- Periodicals; Food -- Periodicals; Food-Processing Industry -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Industrie et commerce -- Canada -- Périodiques; Aliments -- Recherche -- Périodiques; Food industry and trade; Canada; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.foodres.2023.112680
• Languages: English
• ISSNs: 0963-9969

Abstract

Graphical abstract: Highlights: Biocide/phytochemical combinations were assessed by checkerboard and inactivation assays. PAA + GA promoted additive/synergistic effects against planktonic cells. UA was the most promising phytochemical to be combined with biocides. Biofilm cells remained resilient to the antimicrobial effects of all the combinations. Triple combinations caused cell inactivation in a species/biocide dependent manner. Abstract: The failure of current sanitation practices requires the development of effective solutions for microbial control. Although combinations using antibiotics have been extensively studied to look for additive/synergistic effects, biocide combinations are still underexplored. This study aims to evaluate the antimicrobial effectiveness of dual biocide and triple biocide/phytochemical combinations, where phytochemicals are used as quorum sensing (QS) inhibitors. The biocides selected were benzalkonium chloride (BAC) and peracetic acid (PAA) – as commonly used biocides, and glycolic acid (GA) and glyoxal (GO) – as alternative and sustainable biocides. Curcumin (CUR) and 10-undecenoic acid (UA) were the phytochemicals selected, based on their QS inhibition properties. A checkerboard assay was used for the screening of chemical interactions based on the cell growth inhibitory effects against Bacillus cereus and Pseudomonas fluorescens . It was observed that dual biocide combinations resulted in indifference, except the PAA + GA combination, which had a potential additive effect. PAA + GA + CUR and PAA + GA + UA combinations also triggered additive effects. The antimicrobial effects of the combinations were further evaluated on the inactivation of planktonic and biofilm cells after 30 min of exposure. These experiments corroborated the checkerboard results, in which PAA + GA was the most effective combination against planktonic cells (additive/synergistic effects). The antimicrobial effects of triple combinations were species- and biocide-specific. While CUR only potentiate the antimicrobial activity of GA against B. cereus, GA + UA and PAA + GA + UA combinations promoted additional antimicrobial effects against both bacteria. Biofilms were found to be highly tolerant, with modest antimicrobial effects being observed for all the combinations tested. However, this study demonstrated that low doses of biocides can be effective in bacterial control when combining biocides with a QS inhibitor, in particular, the combination of the phytochemical UA (as a QS inhibitor) with GA and PAA.