Application of Cinnamon and Curcumin to Deter E. coli Growth and Increase Antibiotic Susceptibility

Undergraduate #111
Discipline: Biological Sciences
Subcategory: Microbiology/Immunology/Virology

Mason Marshall - University of Kansas
Co-Author(s): Ensaf Taha, Temesgen Samuel, and Teshome Yehualaeshet, Tuskegee University, Tuskegee, AL

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The rapid evolution of antibiotic resistant (ABR) bacteria as well as multi-drug resistant bacteria (MDR) urged scientists to search for alternate ways to combat bacteria. One of these novel approaches is using plant extracts to deter bacterial growth. This study investigated the potential of two plant extracts, transCinnamaldehyde and Curcuma longa Turmeric powder, to inhibit the growth of E. coli while ‘sensitizing’ it to antibiotics and increasing susceptibility. Both compounds were purchased from Sigma-Aldrich. E. coli was treated with cinnamon and curcumin at different concentrations in 96-well plates. Nontreated E. coli cultures served as controls for all parts of the experiment. These plates were then incubated into a Microplate Reader in which the optical density was recorded every 30 minutes for 12 hours at 600 nm. After overnight incubation, a Drop-Dilution from each representative well was performed and the colony-forming units (CFUs) were recorded. Disk-diffusion tests were performed on Iso-Sensitest agar using the antibiotics ampicillin, amoxicillin, bacitracin, and carbenicillin. Discdiffusion tests were carried out to determine if the bacteria had been sensitized to the selected antibiotics. Additionally, MicroScan (automated bacterial susceptibility testing) was performed to investigate further if this sensitization effect applied to additional antibiotics. Curcumin treatments inhibited E coli CFU’s, while higher treatment doses of cinnamon completely eradicated growth. Inhibition zones (IZ) for the diskdiffusion test with curcumin after 24 hours of incubation were larger than the IZ after 3 hours of incubation. The results showed that curcumin “sensitized” E. coli to certain antibiotics. In addition both cinnamon and curcumin treatments showed susceptibility to bacitracin while non-treated controls did not. Curcumin showed a synergistic effect on the MicroScan, increasing susceptibility to numerous antibiotics. Use of additional plant extracts may be a possible method to consider as alternative to commercial antibiotics and as a new way to increase bacterial sensitivity to antibiotics.

Funder Acknowledgement(s): This research was made possible by IBS REU; NSF (Award Number 1263207) and USDA/NIFA (CL # 36 12650 053 62112).

Faculty Advisor: Teshome Yehualaeshet,