Probiotic Characteristics of Pediococcus pentosaceus and Apilactobacillus kunkeei Strains: The lactic Acid Bacteria Isolated from Bangladeshi Natural Honey

Background and Objective: Lactic acid bacteria are known for their strong probiotic effects on the hosts. The probiotic characterization of lactic acid bacteria from Bangladeshi natural honey is limited. The objectives of this study included isolation and assessment of the probiotic and safety characteristics of lactic acid bacteria in Bangladeshi honey. Materials and Methods: Spread and streak plate techniques were used for the bacterial isolation and purification. Isolates were identified using 16S rRNA gene sequence analysis. Agar well diffusion and poisoned food methods were used for antibacterial and antifungal assessments, respectively. Antioxidant activity was carried out based on the microbial free -radical scavenging ability. Microbial autoaggregation, coaggregation and adhesion were assessed using cell sedimentation assay. Blood-agar was used in the hemolytic assay. Antibiotic susceptibility assay was carried out using disc diffusion method. Results and Conclusion: From a total of 25 strains isolated from honey, ten Gram-positive, catalase-negative non-spore-forming isolates were selected and used in agar well diffusion assay. Three of the isolates showed prominent antimicrobial effects with large inhibition zones against all the pathogenic strains, including Bacillus cereus, Staphylococcus aureus, Vibrio cholerae, Salmonella typhi and Candida albicans. Extensive characterization of these isolates was carried out, which revealed their growth and biochemical characteristics and carbohydrate fermentation abilities. Moreover, 16S rRNA gene sequence analysis suggested that the isolates belonged to Pediococcus pentosaceus (two strains) and Apilactobacillus kunkeei. Their tolerance to simulated gastric conditions was assessed in vitro wherein the isolates showed significant survival in low pH, bile salts and phenol. They showed good adhesion ability to ethyl acetate, chloroform and xylene as well as high autoaggregation and coaggregation characteristics. Moreover, free-radical scavenging activity of the isolates suggested the presence of considerable antioxidant effects. In safety assessment, the isolates did not show hemolytic activities and were resistant to several antibiotics. Therefore, these results indicate that honey can be an important source of beneficial lactic acid bacteria species providing several probiotic advantages.