Antibacterial Activity of Three Eco-Enzyme Formulations against Escherichia coli Isolates from Rivers in Ambon City

Contamination by Escherichia coli in aquatic environments indicates microbiological pollution and potential risks to water quality and public health. Eco-enzyme derived from organic waste has potential as a natural antibacterial agent while supporting environmentally friendly waste management. This study aimed to evaluate the antibacterial activity of three eco-enzyme formulations against Escherichia coli isolates from the Wai Batu Gantung (WBG), Wai Batu Merah (WBM), and Wai Tomu (WTM) rivers in Ambon City. The formulations differed in both the number and identity of ingredients, comprising one-, three-, and five-ingredient formulations. Antibacterial activity was assessed using the disc diffusion method. The one-ingredient formulation produced the highest mean inhibition zone diameter (8.50 ± 7.66 mm), followed by the five-ingredient formulation (4.28 ± 4.22 mm) and the three-ingredient formulation (2.33 ± 3.56 mm). However, the Friedman test showed no statistically significant difference in antibacterial activity among the formulations. The effect size, expressed as Kendall’s W, was 0,298. Inhibitory responses also varied among isolates. These findings indicate that the formulations differed descriptively in their observed inhibition zones, but the differences were not statistically significant. Because the formulations varied in both ingredient number and composition, the individual contribution of either factor cannot be determined. Further research should evaluate ingredient composition systematically and account for isolate-level variability to clarify factors associated with antibacterial activity against Escherichia coli.