Isolation and characterization of antimicrobial protein/peptide from leaves of Moringa oleifera (Miracle tree)

Abstract

Moringa oleifera Lam, commonly known as “Drumstick or Miracle Tree”, is a highly nutritious plant having miraculous medicinal properties. Its foliage is rich source of minerals, vitamins and other essential phytochemicals. Leaves are used as potential antioxidant, anticancer, anti-inflammatory, antidiabetic and antimicrobial agent. Present study was on screening of antimicrobial activity and isolation of active proteins from the leaves using different against five bacteria and three fungi (E. coli, B. subtilis, S. aureus, P. vulgaris and P. aeruginosa, A. niger, T. rubrum and Fusarium sp.) using agar well diffusion method. PBS aqueous extract of M. oleifera was antimicrobially most active, and the protein was fractionated with 80% ammonium sulphate followed by ion exchange chromatography. The eluted fraction gave three major peaks (A, B, C) with ‘B’ having the maximum antimicrobial activity and was studied further. The molecular weight of the purified antimicrobial protein/peptide was estimated to be 11 kDa and proved susceptible to inactivation by trypsin and proteinase K. It had maximum antimicrobial activity at 40°C and pH 7 against gram positive (S. aureus), gram negative (E. coli) bacteria and fungus (A. niger).