Biotechnological Characterization and Safety Assessment of Lacticaseibacillus paracasei and Levilactobacillus brevis Strains Carrying entAS-48 and entQ Genes

Abstract

In our previous work, we reported for the first time the presence of enterocin-encoding genes in novel Lacticaseibacillus paracasei (L. paracasei) and Levilactobacillus brevis (Lev. brevis) strains isolated from artisanal dairy products made from raw cow milk. The aim of this study was to isolate enterocin-positive lactic acid bacteria (LAB) from artisanal dairy products and assess their technological characteristics and safety for potential application in food systems. LAB isolates were characterized using phenotypic tests, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) identification, and PCR detection of enterocin genes, followed by evaluation of their physiological and technological properties and a comprehensive safety assessment, including antimicrobial resistance, virulence, biogenic amine, and integron genes. Two strains, L. paracasei S2 and Lev. brevis S62, carried enterocin genes (entAS-48 and entQ) and exhibited strong acidifying and proteolytic activities, along with antibacterial effects against foodborne pathogens and reference strains. Both isolates tolerated environmental stresses, including low pH, and lacked virulence factors, clinically relevant antibiotic resistance genes, biogenic amine production, and integron elements. These results indicate that the strains are safe, multifunctional, and suitable for developing regionally adapted dairy products, highlighting artisanal dairy products as a valuable source of novel LAB with promising biotechnological applications.