Characterization of Probiotic Properties of Lactobacillus Isolates from Traditional Algerian Klila Cheese

Abstract

Background: The Lactobacillus genus represents one of the most prevalent lactic acid bacteria (LAB) species globally. These bacteria are recognized for their probiotic properties, which contribute to human health.

Aims: This study aimed to identify and screen, in vitro, the key probiotic selection criteria of five Lactobacillus strains isolated from "Klila," a traditionally fermented cheese product indigenous to Algeria.

Materials and Methods: The primary probiotic selection criteria were assessed  in vitro using a series of biochemical and physiological assays. These included evaluations of tolerance to low pH, bile salts, and phenol, as well as analyses of auto-aggregation and co-aggregation capacities, cell surface hydrophobicity, antibiotic susceptibility, and antimicrobial activity. Molecular identification, performed through 16S-rRNA gene sequencing, confirmed the five isolates as Lactobacillus plantarum (LP1, LP2, LP3, LP4) and Lactobacillus fermentum (LF1).

Results: Experimental results demonstrated that all five isolates exhibited viability following exposure to low pH (2.2) for three hours. Furthermore, they displayed tolerance to bile salts, with viability ranging from 57.67 to 70.68% and to 0.4% phenol, with viability ranging from 39.22 to 61.01%. Auto-aggregation capacity ranged from 31.35 to 57.38%.  Co-aggregation percentages were observed to vary from 14.57 to 22.17% with Escherichia coli, from 13.04 to 23.62% with Staphylococcus aureus, and from 11.15 to 17.03% with Candida albicans. hydrophobicity towards xylene ranged from 41.67 to 60.47%, while biofilm formation capability ranged from 32.94 to 70.19%. Isolate LF1 exhibited the highest percentages for both hydrophobicity (60.47%) and biofilm formation (70.19%). All five isolates demonstrated significant antioxidant capacities, indicating their potential for applications in food preservation and health promotion. Robust antimicrobial activities were observed against the tested pathogens,  with inhibition zones ranging from 12.6 to 45 mm. A favorable safety profile was established, as none of the isolates exhibited hemolytic, gelatin liquefaction, or coagulase activity.

Conclusion: The Lactobacillus strains isolated from Klila cheese demonstrated physiological characteristics indicative of their potential probiotic candidates with beneficial health implications.

Keywords: Lactobacillus; Lactic Acid Bacteria; Probiotic potential; Antimicrobial activity; Traditional Algerian cheese.