Isolation and Characterization of Enterocin-Producing <i>Enterococcus faecium</i> Strains from Algerian Traditional Food “Dried Figs Marinated in Olive Oil”: Functional and Safety Evaluations

The increasing consumer demand for natural and sustainable food preservation methods has highlighted the potential of lactic acid bacteria (LAB) and their bioactive metabolites, particularly bacteriocins, as effective antimicrobial agents. This study aimed to isolate and characterize <i>Entero...

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Main Authors: Mohamed Merzoug, Keltoum Bendida, Marwa Aireche, Zohra Yasmine Zater, Chaimaa Naila Brakna, Amaria Ilhem Hammadi, Yasmine Saidi, Svetoslav Dimitrov Todorov, Djamal Saidi
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Foods
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Online Access:https://www.mdpi.com/2304-8158/14/5/766
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Summary:The increasing consumer demand for natural and sustainable food preservation methods has highlighted the potential of lactic acid bacteria (LAB) and their bioactive metabolites, particularly bacteriocins, as effective antimicrobial agents. This study aimed to isolate and characterize <i>Enterococcus faecium</i> strains from Algerian traditional dried figs marinated in olive oil, a nutrient-dense and underexplored food matrix. Twelve isolates were identified as <i>E. faecium</i> using MALDI-TOF MS and 16S rRNA gene sequencing, ensuring precise taxonomic classification. Genotypic analyses (BOX-PCR, GTG-PCR, and ERIC-PCR) revealed substantial genetic diversity, with BOX-PCR demonstrating superior discriminatory power. Functional screening confirmed the presence of enterocin genes, including <i>entA</i> (100% of strains), <i>entB</i> (60%), and <i>entL50A</i>/B (20%), which correlated with inhibition zones against <i>Enterococcus faecium</i> VCY, <i>Micrococcus luteus</i> GPE 3001, <i>Staphylococcus aureus</i> ATCC 25923, <i>Pseudomonas aeruginosa</i> ATCC 27853, and <i>Acinetobacter lwoffii</i> GPE 3002. Genotype–phenotype correlation analysis identified strain HFM7 as the most potent antimicrobial strain, exhibiting the largest inhibition zone (20.0 ± 1.0 mm) and harboring three enterocin genes (<i>entA</i>, <i>entL50A</i>, and <i>entL50B</i>). Protease sensitivity confirmed the proteinaceous nature of the antimicrobial compounds. Importantly, no virulence factors (<i>esp</i>, <i>gelE</i>, and <i>hyl</i>) or antibiotic resistance genes (<i>vanA</i>, <i>vanB</i>, <i>ermA</i>, <i>ermB</i>, and <i>aac(6′)-Ie-alph(2″)</i>) were detected, underscoring the safety of these isolates for food applications. These findings suggest that <i>E. faecium</i> strains from traditional foods are promising candidates as natural biopreservatives and starter cultures in clean-label food systems. By bridging traditional food ecosystems and modern biotechnological advancements, this study provides a foundation for sustainable, minimally processed food preservation strategies with potential applications in enhancing food safety and shelf life.
ISSN:2304-8158