Characterization and antimicrobial potential of lactic acid bacteria isolated from fermented figs and wheat against pathogenic bacteria

This study focuses on the isolation and antimicrobial activity screening of lactic acid bacteria (LAB) strains from fermented wheat "Hamoum" and figs soaked in olive oil, both traditional products from western Algeria, as well as their ability to produce bacteriocins.The use of these LAB strains, derived from natural and local sources, represents an eco-friendly and safe alternative to conventional chemical preservatives in the fight against pathogenic bacteria.The antimicrobial activity of LAB isolates against both Gram-positive and Gram-negative pathogens (Pseudomonas aeruginosa, E. coli, Staphylococcus aureus, Listeria monocytogenes, and Listeria innocua) was evaluated using the well diffusion method on soft agar.Treatment of the inhibitory substances with proteolytic enzymes (proteinase K and trypsin) confirmed their proteinaceous nature, indicating they are likely bacteriocins.These molecules also exhibited remarkable stability under extreme pH (pH 2) and temperature conditions (4 C and 80 C), making them suitable for industrial applications.Furthermore, EDTA, Tween 80, and HO were found to enhance the antimicrobial activity, while SDS and Triton X-100 partially inhibited it.Due to their strong activity against Listeria species and physicochemical stability, these bacteriocins are classified as class IIa, making them promising candidates for use as natural biopreservatives.