Characterization of Lacticaseibacilus rhamnosus of Honey Origin from Saudi Arabia: Potential Probiotic Strains with Antibacterial Effects

Background: We recently isolated five strains of lactic acid bacteria (LAB) from honey and identified them via 16S ribosomal RNA gene sequencing. The sequences were deposited in the NCBI GenBank database and given the corresponding accession numbers: OL539410 to OL539414. Since LAB are well known for their probiotic properties, in this study, we characterized the probiotic potential and safety of these isolates. Methods: Five LAB strains, including two strains of Lacticaseibacillus rhamnosus and three strains of Enterococcus faecium isolated from honey samples, were examined for their probiotic potential through acid and bile salt resistance assays, bacterial cell surface hydrophobicity, autoaggregation, and coaggregation assays. In addition, cell free culture supernatant antibacterial activity of mentioned LAB strains was tested against E. coli (ATCC 25922), P. aeruginosa (ATCC 27853), K. pneumoniae (ATCC 13883), S. aureus (ATCC 25923), S. epidermidis (ATCC 12228), and S. pneumoniae (ATCC 6303) Further tests, such as those measuring hemolytic activity and antibiotic susceptibility, were also performed to evaluate their safety profile. Results: All the LAB strains tolerated and survived the simulated gastrointestinal conditions: pepsin at acidic pH (3.0) and bile salt concentration (0.3%) at alkaline pH (8.0), with different levels of viability. According to antibacterial assays, L. rhamnosus (P0-2 L) and E. faecium (P0-4 L) exhibited the strongest inhibitory activities. Also, L. rhamnosus (P0-2 L) demonstrated high adhesive and aggregative properties. All strains tested negative for hemolytic activity, indicating safety for human consumption. Conclusion: This study revealed that L. rhamnosus derived from Sidr honey may be used as a potential probiotic. This study also showed that honey from different regions can contain probiotics.