Hazelle Mar Y. Alvarado1 , Judyan M. Pancho1,Frecy Rose M. Tesara1, Jay G. Caponpon1 ,Jecelle Lou F. Alajas1, Noraisa E. Salipada1,Anwar M. Lingga1'2 Floriele M. Gonzaga2, Floriefe M. Gonzaga-Torino1
1College of Fisheries, Mindanao State University – Buug, Datu Panas, Buug, Zamboanga Sibugay, 7009 Philippines., 2 Ghent University, 9000, Gent, Belgium
Email: floriefe.torino@msubuug.edu.ph
ABSTRACT
This study investigated the antibacterial properties of calamansi (Citrus microcarpa) peel extract (CPE) at varying concentrations using the disk diffusion method. The primary objective was to evaluate its effectiveness in inhibiting bacterial growth in pond water used for tilapia (Oreochromis sp.) culture. Five treatments were applied, including a control (0%), pure calamansi peel extract (100%), and three diluted concentrations (0.5%, 1%, and 2%). Water samples from the pond, containing natural populations of heterotrophic bacteria commonly present in freshwater aquaculture systems, were used for bacterial inoculation. The antibacterial activity was assessed by measuring the inhibition zones around filter paper disks soaked in the extract. Results demonstrated that the pure CPE exhibited the highest antibacterial activity, with consistent inhibition zones across all trials. In contrast, the lower concentrations produced inconsistent and minimal inhibition effects. The control treatment showed no bacterial inhibition, confirming the absence of external antibacterial influences. The findings suggest that while pure CPE as the potential to serve as a natural antibacterial agent, the diluted concentrations are not effective for bacterial control in aquaculture systems. Further research is recommended to identify the active bioactive compounds, optimize the extract’s formulation, and evaluate its long-term effects on aquatic microbial communities. By repurposing agricultural waste such as calamansi peels, this study contributes to SDG 12 (Responsible Consumption and Production) and SDG 14 (Life Below Water) through promoting sustainable aquaculture practices. The antibacterial potential of CPE also supports SDG 3 (Good Health and Well-being) by reducing reliance on synthetic antibiotics and mitigating the spread of antimicrobial resistance. Moreover, the use of natural antimicrobials in aquatic systems aligns with SDG 6 (Clean Water and Sanitation), helping ensure healthier aquatic environments.
Keywords: Calamansi Peel Extract, Antibacterial Activity, Disk Diffusion Method, Aquaculture, Natural Antibiotics