Metabolic profiles of Weissella spp. postbiotics with anti-microbial and anti-oxidant effects

This present study aimed to isolate beneficial bacteria from honey bee pollen microbiota and to investigate the metabolite profiles of postbiotics exhibiting anti-microbial and anti-oxidant properties.

Pour plate technique was used to isolate bacteria from honey bee (Apis mellifera L.) pollen samples. Different colonies grown on agar plates were selected and screened for their anti-microbial activity against important pathogens using agar well diffusion assay. The isolates that exhibited remarkable inhibitory effects against all tested pathogens were identified by 16S rRNA sequence analysis. DPPH (2, 2-diphenyl-1-picrylhydrazil) free radical scavenging assays were used to assess the antioxidant capacity of their postbiotics. Besides, the total phenolic and total flavonoid compounds in postbiotics were determined as gallic acid and quercetin equivalents, respectively. The valuable metabolites in postbiotics were also profiled using chromatographic tools and Mass Spectrophotometry (MS) analysis.

Twenty-seven strains were isolated from different honey bee pollen samples. 16 out of the 27 strains exhibited antagonistic activity against at least one reference strain of pathogens, tested. The most effective strains belonging to the genus Weissella were identified as W. cibaria and W. confusa. Postbiotics above 10 mg/mL exhibited higher radical scavenging activity and high total phenolic and total flavonoid contents. MS analysis demonstrated that metabolites in postbiotics derived from Weissella spp. were found very similar to the metabolites found in honeybee pollen.

The outcomes of this study revealed that honey bee pollen could be considered a potential source for the bacteria which produce anti-microbial and anti-oxidant agents. The similarity with the nutritional dynamics of honey bee pollen also indicated that postbiotics could also be used as novel and sustainable food supplements.