Determination of antioxidant capacity and antimicrobial activity of bee pollen and basil (Ocimum basilicum L.) essential oil combination

The main cause of spoilage in food products is microorganisms. It has become difficult to combat these spoilage factors, which develop resistance to antimicrobial agents day by day. To combat this situation, one of the ways to use antimicrobial substances together is to reduce the doses used and to make it more difficult for microorganisms to gain resistance with a synergistic effect. In this thesis study, the antimicrobial and antioxidant effects of the essential oil obtained from the dried leaves of basil (Ocimum basilicum L.), known for its strong antimicrobial and antioxidant properties, and bee pollen were examined. TPC and DPPH analyzes were performed to investigate the total phenolic substance amount and antioxidant capacity of these components. As a result of the analyses, it was determined that the total phenolic substance content of bee pollen and basil essential oil was 90.132 mg gallic acid equivalent GAE/100 g and 10292.668 mg GAE/100 g, respectively. Broth microdilution method and agar well diffusion method were used to determine antimicrobial activity. In the MIC and MBK analyzes performed with bee pollen and basil essential oil, the lowest value was determined on K. pneumaniae. C. parapsilosis (clinical isolate) was determined as the microorganism with the highest MIC and MBC values. As a result of agar well diffusion analysis, it was determined that the bacteria most resistant to 800 mg/mL bee pollen application were Gram-negative bacteria E. coli ATCC 25922 and S. typhimurium ATCC 14028. When the effects of AP were examined, it was observed that it could not create zones on the test yeasts (S. cerevisiae and C. parapsilosis). It was determined that the most sensitive bacterium was K. pneumoniae with a zone diameter of 9.25 mm. It was determined that basil essential oil did not create zones on Gram-negative bacteria L. monocytogenes ATCC 7644, yeasts S. cerevisiae and C. parapsilosis when applied at 40 µL/mL. It was determined that the most sensitive bacterium against basil essential oil was K. pneumoniae with a zone diameter of 9.47 mm. Fractional Inhibition Concentration (FIC) analysis was performed to determine the synergistic effect of bee pollen and basil essential oil together as antimicrobial agents. As a result of the analysis, it was determined that the two antimicrobial substances did not show a synergistic effect together, they showed a differential effect on B. cereus ATCC 10876, S. aureus ATCC 25923 and S. epidermidis ATCC 12228, but an antagonist effect on all other bacteria.