Mining indigenous honeybee gut microbiota for Lactobacillus with probiotic potential

Probiotic Potential of Enterococcus lactis GL3 Strain Isolated from Honeybee (Apis mellifera L.) Larvae: Insights into Its Antimicrobial Activity Against Paenibacillus larvae

This study aimed to address the need for effective probiotics and antibacterial agents to combat American foulbrood disease in honeybees, caused by Paenibacillus larvae. In the context of declining honeybee populations due to pathogens, we isolated eight lactic acid bacteria (LAB) strains from honeybee larvae (Apis mellifera L.) and evaluated their probiotic potential and inhibitory effects against P. larvae. Methods included probiotic property assessments, such as acid and bile salt resistance, hydrophobicity, auto-aggregation, co-aggregation with P. larvae, antioxidant capacities, osmotolerance to 50% sucrose, and antibiotic susceptibility. Results indicated that the GL3 strain exhibited superior probiotic attributes and potent inhibitory effects on P. larvae. Whole-genome sequencing revealed GL3 to be an Enterococcus lactis strain with genetic features tailored to the honeybee larval gut environment. Pangenome analysis highlighted genetic diversity among E. lactis strains, while molecular docking analysis identified aborycin, a lasso peptide produced by GL3, as a promising inhibitor of bacterial cell wall synthesis. These findings suggested that GL3 was a promising probiotic candidate and antibacterial agent for honeybee health management, warranting further investigation into its in vivo efficacy and potential applications in beekeeping practices.

Inhibiting potential of selected lactic acid bacteria isolated from Costa Rican agro-industrial waste against Salmonella sp. in yogurt

This study aimed to characterize lactic acid bacteria (LAB) isolated from Costa Rican agro-industrial waste and explore their bioprotective potential against Salmonella in yogurt. A total of 43 LAB isolates were identified using the 16S rRNA region. In vitro inhibition of Salmonella, Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli was determined. A total of 15 of the 43 isolates showed a good to strong antimicrobial effect against at least two pathogens. A total of 14 selected isolates were evaluated for antibiotic resistance, gelatinase, and hemolytic activity. The bioprotective effect of the most promising strain, Lactiplantibacillus pentosus, was assessed against Salmonella sp. during yogurt fermentation. All the isolates were resistant to vancomycin and showed variable degrees of susceptibility to other antibiotics. All of the isolates were negative for gelatinase, and 5 isolates had no hemolytic activity. A significant inhibitory effect of L. pentosus_58(6)-2I (p<0.05) against Salmonella during fermentation was found, but pathogen reduction was limited to 0.611 log CFU/mL.

Characterization of Lactic Acid Bacteria Strains Isolated from Algerian Honeybee and Honey and Exploration of Their Potential Probiotic and Functional Features for Human Use

Using culture enrichment methods, 100 strains of bacilli of lactic acid bacteria (LAB) were isolated from honeybee Apis mellifera intermissa and fresh honey, collected from apiaries located in the north-east of Algeria. Amongst all of the isolated LAB, 19 selected strains were closely affiliated to four species-Fructobacillus fructosus (10), Apilactobacillus kunkeei (5), Lactobacillus kimbladii and/or Lactobacillus kullabergensis (4)-using phylogenetic and phenotypic approaches. The in vitro probiotic characteristics (simulated gastrointestinal fluids tolerance, autoaggregation and hydrophobicity abilities, antimicrobial activity and cholesterol reduction) and safety properties (hemolytic activity, antibiotic resistance and absence of biogenic amines) were evaluated. The results indicated that some strains showed promising potential probiotic properties. In addition, neither hemolytic activity nor biogenic amines were produced. The carbohydrate fermentation test (API 50 CHL) revealed that the strains could efficiently use a broad range of carbohydrates; additionally, four strains belonging to Apilactobacillus kunkeei and Fructobacillus fructosus were found to be exopolysaccharides (EPS) producers. This study demonstrates the honeybee Apis mellifera intermissa and one of her products as a reservoir for novel LAB with potential probiotic features, suggesting suitability for promoting host health.

Honeybee-associated lactic acid bacteria and their probiotic potential for human use

This study aims to identify lactic acid bacteria (LAB) isolated from honeybees (Apis mellifera workers and larvae) in detail and to determine their functional probiotic properties. A total of 11 strains were classified based on morphological and biochemical characteristics. Preliminary probiotic properties of strains, that were molecularly identified using 16 S rRNA, such as antimicrobial activity, tolerance to digestive conditions, aggregation ability, were investigated. The antimicrobial properties of strains were tested against a wide range of human pathogens. All strains that showed γ-hemolysis and did not contain bacteriophages were considered safe. The strains' survivability checked for 0.3% bile and 3.0-7.8 pH contents was promising. The highest autoaggregation ranged from 14.7 to 30.76% after 4 h. Tested LAB strains markedly exhibited coaggregation with Listeria monocytogenes and Escherichia coli. According to the results, tested bacteria showed significant antagonistic effects against pathogens, and positive probiotic characteristics compatible with in vitro gastrointestinal tract conditions. The results suggest that Apis mellifera LAB symbionts may have a probiotic potential, and be effective and safe candidates for human use. This study provides an addition to the development of the current knowledge by defining in detail honeybee-associated bacteria and determining their probiotic potential.