University of Santo Tomas
Senior High School
Science, Technology, Engineering, and Mathematics
Abegail Marie B. Delin, Kristian S. Delos Santos, Allen Miguel F. Dimayacyac,
Nicole Francesca D. Dizon, and Hannah Therese C. Eranzo
Abstract
Cymbopogon citratus has been shown by previous studies to be effective against certain gram-positive bacteria and to possess various phytochemical compounds with antimicrobial properties. Gram-positive bacteria are found everywhere and can cause many types of infections and are transmitted to humans in a variety of ways such as contact with infected people and contaminated surfaces including food and water. Because of this, the researchers have decided to test the antimicrobial activities of Cymbopogon citratus against Mycobacterium phlei. C. citratus leaves were air-dried for eight (8) days and was macerated for two (2) days. Phytochemical analysis and antimicrobial testing against Mycobacterium phlei , a type of gram-positive bacteria, were conducted on concentrated C. citratus with 95% ethanolic extract. Flavonoids, polyphenols, and tannins were shown to be present and were shown to possess antimicrobial activities against
M. phlei. Through the Kirby-Bauer disk diffusion test, three (3) equidistant wells were arranged on the Nutrient Agar (NA) plate then, 200 μl of the C. citratus sample was placed in each well.
The agar plates were incubated at 35°C and observed after 24 hours. The antimicrobial index
(AI) was found to be at 0.3. This study shows that C. citratus may have the potential to cure diseases caused by bacteria under the Mycobacterium genome, which have cell walls and metabolisms that are very different from other bacteria.

Keywords : Antimicrobial activity, Lemongrass extract, Mycobacterium phlei , Maceration, Kirby-Bauer disk diffusion test