Evaluation of antibacterial activity of four medicinal plant leaf extracts against Pectobacterium sp. causing soft rot in potato

This study was conducted to determine the antibacterial activity of the ethanol and acetone leaf extracts of Argyreia pomacea, Coccinia grandis, Erythrina subumbrans and Gymnema sylvestre against the causal pathogen of potato soft rot. Pathogen was isolated from soft rot potato which was identified as Pectobacterium sp.. The pathogenicity of the isolated Pectobacterium sp. was confirmed on healthy samples of potatoes. The antibacterial activity of leaf extracts was determined by agar well diffusion assay. The leaf extracts were tested at different concentrations of 200, 100, and 50 mg/mL. Based on the results, the acetone and ethanol extracts of E. subumbrans, the ethanol extract of G. sylvestre, and both extracts of C. grandis at 200 mg/mL possess potent antibacterial compounds against Pectobacterium sp.. There were no significant differences in zone of inhibition among these treatments. Therefore, further studies are necessary to isolate and identify the specific bioactive compounds in the leaves that are responsible for the observed antibacterial effects.