A study of antimicrobial activities of aqueous and ethanolic extract of bee pollen against

Abstract Background Ethiopia is one of the plant species-rich countries in the world and the center of origin of many medicinal plants. Studying antimicrobial activities of pollen is vivacious to investigate plant resources for medicinal values and the study was conducted to evaluate antimicrobial properties of bee pollen against mentioned bacteria. Methods Completely Randomized Design was used for laboratory work. After adjusting turbidity, consistent growth of bacterial culture was made using a sterilized cotton swab. 20 grams of bee pollen was added to 200 ml of distilled water as well as ethanol and finally, the extract was filtered by Whatman filter by paper, dried and weighted and stock solutions were made as follows,3.6 gm. was added to 12 ml of distilled water to prepare stock solutions as follows 3.6:12 = 0.3 x \({10}^{6}\) = 3 x \({10}^{5}\) ppm stock solution and antimicrobial activities of pollen were tested against mentioned bacteria. Data were imported to R software version 3.44. Multilevel analysis was used to see the interaction between bacteria species and each concentration of pollen and Anova was used to see the significance of these concentrations on bacteria species. A p-value of < 0.05 was considered statistically significant. Results Results indicated that bacteria were more inhibited at 72 hours than 48 and 24 hours and the results showed an ethanolic extract of bee pollen had antimicrobial activities against both Gram-negative and Gram-positive bacteria mentioned above. Time has significant effects on tested bacteria (p = 0.000) and treatments have significant effects on tested organisms (p = 0.000). The ethanolic extract inhibited the growth of more Gram-negative bacteria: Escherichia coli and Shigella boydii. Bacillus subtilis was mostly inhibited by aqueous extract of bee pollen than others. Conclusions Ethanolic extract of pollen had antibacterial activities against all tested bacterial strains even though it is concentration and time-based. The ethanolic extract inhibited more Gram-negative bacteria relatively while aqueous extract inhibited more Gram-positive relatively. Negative controls (sterilized water) didn’t show any antimicrobial properties, while positive control (Chloramphenicol) had antimicrobial activities. Further isolation and characterization of bioactive compounds from pollen are useful to develop a novel botanical formulation for further applications from the pollen of medicinal plants.