African Journal of Agricultural Economics and Rural Development

African Journal of Agricultural Economics and Rural Development ISSN: 2375-0693 Vol. 11 (1), pp. 001-005, January, 2023. © International Scholars Journals

Full Length Research Paper

Identification and primary characterization of a plant antimicrobial peptide with remarkable inhibitory effects against antibiotic resistant bacteria

Atousa Aliahmadi1,2, Rasoul Roghanian1*, Giti Emtiazi1, Fatemeh Mirzajani3 and Alireza Ghassempour3

1Department of Biology, Faculty of Science, University of Isfahan, Hezarjarib, Isfahan, Iran.

2Department of Biology, Medicinal Plants and drug Research Institute, Shahid Beheshti University.

3Department of Phytochemistry, Medicinal Plants and drug Research Institute, Shahid Beheshti University, Iran.

Accepted 20 January, 2023


On the basis of a primary screening scheme by using plant seed methanol extract against a collection of human pathogenic bacteria, Medicago sativa L. seeds were chosen as the best potential resource against tested Gram positive bacteria. Then an agar-overlay method using fully separated proteins on sodium dodecyl sulphate-polyacryliamide gel electrophoresis (SDS-PAGE) gels was used for initial determination and primary characterization of active putative defensins in the plant seeds. Clear and remarkable zones of inhibition in a region corresponding to peptides slightly larger than 6 kDa were recorded for Methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococcus faecium (VRE) strains and yeast but a smaller inhibition zone with several colonies for tested Gram negative strain of Escherichia coli. Further characterization experiments using two-dimensional gel electrophoresis and subsequent agar-overlay assay against both strains confirmed the peptide nature of the active substance. Also gel filtration separation using Sephadex G-25 superfine and subsequent antibacterial assays could confirm the presence of a low molecular weight anti-MRSA and anti-VRE peptide in the total water soluble proteins obtained from M. sativa L. seeds which also showed high level of thermo stability.

Key words: Medicago sativa L., methicillin resistant bacteria, vancomycin resistant bacteria, plant defensins.