Abstract
Consumption of ready-to-eat chopped fruits sold in the streets is a concern, as such activities are outside the regulation and protection in most developing countries. Ready-to-eat mangos are commonly sold as wedges in plastic cups at ambient temperature by mobile vendors in Ecuador, thus they are prone to contamination by bacteria, which poses a safety issue of concern. This work aimed to evaluate the effect of several antimicrobial cocktails consisting of previously designed specific peptide extract combinations from two probiotic bacteria Lactobacillus plantarum UTNCys5-4 and Lactococcus lactis subsp. lactis UTNGt28, along with nisin, a commercial food additive, on mango wedges artificially inoculated with a logarithmic phase culture of a five-strain bacterial mixture (FSBM). Preliminary bacteriological analysis of mango wedges purchased from mobile vendors showed the presence of multiple antibiotic-resistant isolates such E. coli spp., Enterobacter spp., Shigella spp., Salmonella spp., along with yeasts and molds, indicating non-compliance with the food safety standards. The results revealed that two antimicrobial cocktails, T2 and T5, containing cell-free supernatant based (CFS) and precipitated peptides (PP) based cocktails from UTNCys5-4 and UTNGt28 strains applied at dose 1:3 (v/v), were the most efficient combinations that inhibited the colonization of total bacterial counts with 56.03% and 55.61% in mango wedges stored with refrigeration. The reduction of total E. coli counts was 64.93%, while Salmonella and Shigella counts were reduced by 98.09% and 97.93%, respectively, when mango wedges were treated with T5-cocktail. The commercial nisin inhibited total Salmonella spp. counts by 40.13%, while E. coli spp. and Shigella spp. diminished by 28.20% and 37.22%, respectively. Moreover, we showed that T5 but not T7 (nisin) damaged the target cell integrity, thereby eventually inhibiting their growth and reproduction. The selected antimicrobial cocktails exerted a bacteriolytic effect by killing the FSBM simultaneously in a fruit matrix and preventing their accumulation in mango wedges. Furthermore, there is a possibility of using peptide combinatorial treatments to combat drug-resistant bacteria in ready-to-eat fruits.
Highlights
Mango Wedges Sold by Mobile Vendors Hold Antibiotic-Resistant Microorganisms
The results indicated the presence of several indicator bacteria and their amount was linked to the fruit ripening stage and purchasing origin (V1, V2)
This study drew attention to the contamination of tropical ready-to-eat mango wedges with antibiotic-resistant bacteria that could be acquired during manipulation by street vendors
Summary
A megabiodiverse country, is an ideal place for tropical fruit lovers, where you can find myriad varieties of fruits with unique flavors. Due to the high climatic variation and tropical temperature, the fruits are commercialized throughout the year. Mango (Mangifera indica) is one of the most important tropical fruits in the world, as ascorbic acid, carotenoids, polyphenols, and antioxidants are present in the edible part of the fruit [1]. Mango production in Ecuador dates back dozens of years as a highly desirable seasonal fruit, with an exquisite sweet taste, especially the traditional variety
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