Article info.

ABSTRACT

Received 21 Nov 2019
Revised 27 Apr 2020

Accepted 31 Jul 2020

In this study, the antimicrobial activities of cinnamon oil (Cinnamomum cassia), acetic acid, and lactic acid, alone or in combination, against Escherichia coli ATCC 23631 were evaluated by the agar disk diffusion, broth dilution, and UV absorption determination methods. In the agar disk diffusion assays, using the antibiotics ampicillin and nalidixic acid as the positive control, all three agents tested exhibited an effective inhibition against E. coli with inhibition zones ranging from 3.00 to 15.33 mm, compared to those of ampicillin and nalidixic acid ranging from 0.00 to 12.00 mm. In the broth dilution assays, the MBC (minimum bactericidal concentration) values of cinnamon oil and organic acid were determined from 300 to 5,000 ppm in which cinnamon oil giving the best result. In both assays, acetic acid and lactic acid showed similar antimicrobial activities, which are lower than those of cinnamon oil or their combinations. The assays also suggested that the combinations of cinnamon oil and lactic acid showed a higher synergic effect than those of cinnamon oil and acetic acid. Although the antimicrobial activities of the combinations of cinnamon oil with the organic acids were not higher than using the pure oil, the use of these combinations would reduce the essential oil amount needed to inhibit E. coli.

Keywords

Acetic acid, antimicrobial activity, cinnamon oil, Escherichia coli, lactic acid

Cited as: Dong, L.M. and Thuy, D.T.K., 2020. Inhibitory effects of cinnamon oil, acetic acid, and lactic acid on Escherichia coli ATCC 23631. Can Tho University Journal of Science. 12(2): 33-39.