Peptide-Based Formulation from Lactic Acid Bacteria Impairs the Pathogen Growth in <i>Ananas Comosus</i> (Pineapple)

• Main Authors: Gabriela N. Tenea, Daniela Olmedo, Clara Ortega
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: Coatings
• Subjects: peptides; lactic acid bacteria; pineapple; antimicrobial; bacteriolytic; TEM
• Online Access: https://www.mdpi.com/2079-6412/10/5/457

Worldwide, street vending commerce has grown exponentially, representing in some countries, including Ecuador, a significant proportion of food consumed by the urban population. Pineapple is one of the common fruits sold as ready-to-eat slices by ambulant vendors in the street or on public transport at risk of contamination by various microorganisms. Previously, we selected <i>Lactobacillus plantarum</i> UTNCys5-4 and <i>Lactococcus lactis</i> subsp. <i>lactis</i> Gt28 strains producing peptides with high capacity to inhibit pathogen growth in vitro. In this study, the effect of different edited formulations containing a mixture of Cys5-4/Gt28 peptides was evaluated in vitro and ex vitro against a pathogenic cocktail containing <i>E. coli (2)</i>, <i>Salmonella (2)</i> and <i>Shigella (1)</i>. The growth of bacterial cocktail co-inoculated with cell-free supernatant containing peptides (formulation T1) and precipitated peptides (formulation T6), in a ratio of Cys5-4/Gt28:1:1 (<i>v/v</i>), results in a decrease of total cell viability with 1.85 and 1.2 log CFU/mL orders of magnitude at 6 h of incubation. About the same decrease (1.9 log CFU/g) was observed when pineapple slices artificially inoculated with the pathogenic cocktail were coated with T1 formulation, indicating the capacity to diminish simultaneous pathogens <i>in situ</i>, thus demonstrating its great biological control and protection. However, the <i>E. coli</i> cell counts reduced by 2.08 log CFU/g while <i>Salmonella</i> and <i>Shigella</i> cell counts reduced by 1.43 and 1.91 log CFU/g, respectively, at 5 days of refrigeration. In the untreated pineapple slices, the total cell density was maintained during storage, suggesting the adaptation of the pathogens to the fruit matrix. The peptide-based formulation exerted a bacteriolytic mode of action inducing pathogenic cell death. The results indicate that coating pineapple slices with peptide-based formulation is a promising approach to protect them from further contamination by microbial spoilage as well as an alternative to increase the food safety.