Authors: Rolime Grace Okias1, Mark Marvin A. Roa1, Joeylene Plaza1, and Jether P. Sumpo2
1Secondary Education Department, College of Education, 2Natural Sciences and Mathematics Department,
College of Arts and Sciences Mindanao State University Buug, Datu Panas, Buug, Zamboanga Sibugay, Philippines
Email: rolimegrace17@gmail.com, jether.sumpo@msubuug.edu.ph
ABSTRACT
Escherichia coli is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia
commonly found in the lower intestine of warm-blooded organisms. A study was conducted to determine the significant
difference on the bac-tericidal effect of various plant extracts on the Escherichia coli in terms of the zone of exclusion.
The treatments used are the fol-lowing: distilled water, calamondin extract, garlic extract, gotu kola extract; and combination
of all extracts. The application of the treatments was done through Disk-diffusion Method. Disks of filter paper were impregnated
with a specific plant extract and placed on the agar plate that have been previously inoculated with E. coli. Data were collected by measuring the diameter of the clear zone in terms of millimeters. Based on the results of the study, there is a significant difference on the bactericidal effect of various plant extracts on E. coli and that the calamondin extract shows the greatest inhibitory effect on the growth of Escherichia coli. This is maybe because calamondin extract contains sinapic acid which shows antioxidant, antimicrobial, anti-inflammatory, anticancer, and anti-anxiety activity (Niciforovic and Abramovic, 2014). Based on the conclusions made, it is recommended that calamondin extract could be used as treatment for E. coli related infections.
Keywords: bioassay, bactericidal effect, diffusion method, zone of exclusion