<![CDATA[Ageratum conyzoides L., commonly known as bandotan, is a medicinal plant traditionally used by Indonesian communities to treat stomach disorders and cleanse fresh wounds. Bacillus cereus, a Gram-positive bacterium, is responsible for food poisoning, causing symptoms such as vomiting and diarrhea. This bacterium is widespread in the environment and produces spores that are more resistant to environmental stress than its vegetative cells. The present study aimed to evaluate the antibacterial activity of methanol extracts from A. conyzoides leaves and to determine the most effective concentration against Bacillus cereus. Extracts were tested at concentrations of 25%, 50%, 75%, and 100%, with amoxicillin serving as a positive control and 10% dimethyl sulfoxide (DMSO) as a negative control. Antibacterial efficacy was assessed by measuring the diameter of inhibition zones using the well diffusion method on Mueller Hinton Agar (MHA), and the data were analyzed using Analysis of Variance (ANOVA). The results showed that the methanol extract exhibited antibacterial activity at all tested concentrations, ranging from 25% to 100%. The highest inhibition zone, measuring 21.73 ± 3.21 mm after 48 hours of incubation, was observed at the 100% concentration and classified as very strong. The minimum effective concentration was 25%, which produced an inhibition zone of 12.83 ± 1.30 mm, categorized as strong. These findings indicate that A. conyzoides leaf extracts have significant potential as natural antibacterial agents, particularly for controlling Bacillus cereus.]]>
