The Inhibitory Potential of Wild Horse Milk with Varying Incubation Periods Against Escherichia coli and Staphylococcus aureus

Abstract

Sumbawa wild horse milk is believed to contain bioactive compounds with antimicrobial properties and Lactic Acid Bacteria (LAB) that enable the milk to undergo autofermentation, producing antimicrobial metabolites capable of inhibiting bacterial growth. The objective of this study was to determine the antimicrobial potential of Sumbawa wild horse milk in inhibiting the growth of Escherichia coli and Staphylococcus aureus colonies in vitro. This study utilized four milk samples from four different horses originating from Sumbawa Island, divided into five treatment groups: I1 (non-incubated milk), I2 (milk incubated for 12 hours), I3 (milk incubated for 24 hours), I4 (milk incubated for 36 hours), and I5 (milk incubated for 48 hours). Two control groups were used: ciprofloxacin (K-) as a positive control and distilled water (K+) as a negative control. The antibacterial potential was tested using the well diffusion method, and the diameter of the inhibition zone (DIZ) was measured with a caliper. Data were analyzed using a One-Way ANOVA followed by Tukey's test when significant differences were found. The results showed that, in general, DIZ measurements indicated a significant difference (p<0.05) between the horse milk groups and the K- and K+ control groups. However, variations in incubation time among the horse milk groups (I1, I2, I3, I4, I5) did not show any statistically significant differences (p>0.05). In conclusion, both non-incubated and incubated Sumbawa wild horse milk (up to 48 hours) exhibited equally effective inhibitory activity against bacterial colony growth.