Genotypic characterization and antimicrobial potential of bacteria of technological interest isolated from local dairy products of western Algeria

Abstract

The present study aimed to isolate lactic acid bacteria (LAB) from Algerian artisanal dairy products, identify them using MALDI-TOF MS, screen for bacteriocin-producing strains, evaluate their biochemical and biotechnological properties, and assess their biosafety profile. A total of twenty-nine bacterial strains were isolated from various artisanal dairy products. MALDI-TOF analysis identified three species: Lacticaseibacillus paracasei (L. paracasei, n=19), Levilactobacillus brevis (Lev. brevis, n=8), and Enterococcus faecalis (E. faecalis, n=2). Molecular screening of twelve enterocin-encoding genes revealed the presence of entAS-48, entQ, and ent1071A/B in thirteen isolates, with one strain harboring both entAS-48 and entQ genes. All isolates tolerated acidic environement. Most isolates exhibited strong antibacterial activity against six reference bacterial strains, with inhibition zones ranging from 10.67 ± 0.58 mm to 27.00 ± 0.00 mm, and moderate activity against multidrug-resistant (MDR) Enterobacteriaceae. Furthermore, all L. paracasei and Lev. brevis strains carrying enterocin-encoding genes exhibited potent antimicrobial activity against the evaluated pathogenic microorganisms. Biosafety assessment showed that all strains lacked genes associated with biogenic amine production and integron elements. Screening for virulence and antibiotic resistance genes revealed the presence of the hyl gene in L. paracasei S8, while the esp gene was absent. The hyl-positive isolate also carried the entAS48 gene. Additionally, the msrA gene was detected in L. paracasei S93, which also harbored the ent1071A/B gene. Overall, most isolates lacked clinically relevant virulence factors and antibiotic resistance genes, confirming their safety. This study represents the first report of enterocin-encoding genes in L. paracasei and Lev. brevis strains. The findings highlight the multifunctional properties and favorable safety profiles of these LAB, supporting their potential application as natural biopreservatives and starter cultures in food production, thereby contributing to improved food quality and consumer protection.