Identification, phenotypic characterization and assessment of potential probiotic properties of lactic acid bacteria isolated from the Algerian traditional cheese “El-Klila”

Abstract El-Klila is a popular, traditional, spontaneously fermented Algerian cheese. Here, we report the identification and characterization of lactic acid bacteria isolated from El-Klila. A total of 26 isolates were identified, typed and several phenotypic traits were determined to assess their potential as putative probiotics using a combination of pheno- and genotypic methods. Using initial phenotypic characterization followed by rep-PCR-fingerprinting, as well as 16S rRNA and recA gene sequencing, the isolates were identified as Lactiplantibacillus plantarum (73% of isolates), Lacticaseibacillus paracasei (23%) and Limosilactobacillus fermentum (4%). All strains were resistant to vancomycin except Lb. fermentum Kb2, and some isolates like Lc. paracasei K2 were resistant to all antibiotics tested. A total of 69% of the isolates survived 30 minutes at pH 2, 81% excreted bile salt hydrolase enzymes, and 69% produced exopolysaccharide. All strains were found to inhibit one or more of the tested pathogens (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Listeria innocua). Further investigation of the underlying mechanism of the antimicrobial activity showed that it was due to acid production. However, Lb. fermentum Kb2 produced an unknown high-molecular-weight, heat-stable bacteriocin-like molecule that significantly inhibited Listeria innocua. Lactiplantibacillus plantarum B3 exhibited better survival in simulated gastric juice and increased transepithelial electrical resistance (TER). Similarly, Lc. paracasei K2 also demonstrated a significant increase in TER relative to the other tested isolates. Importantly, the culture supernatant of Lb. fermentum Kb2 enhanced the relative TER of Caco-2 monolayer over 24 h, and it was sensitive to all antibiotics tested, indicating a desirable safety profile. Based on our findings, a considerable number of novel lactobacilli strains from Algerian cheese “El-Klila” possess properties in vitro that are desirable for putative probiotics.