Anti-bacterial activity of Ricinus communis L. against bacterial pathogens Escherichia coli and Klebsiella oxytoca as evaluated by Transmission electron microscopy

The emergence of multidrug-resistant (MDR) microbes has become one of the major threat globally. Infectious diseases are the second leading cause of death, two-third of which are caused by Gram-negative bacteria. The increasing number of multidrug resistant (MDR) microbes is quite alarming and has raised the necessity of development of new antibacterial drugs. Escherichia coli and Klebsiella have been reported among the top most resistance-developing pathogens. Ricinus communis is an important medicinal plant reported to possess antimicrobial phytochemicals such as α-pinene. The hexane treated crude ethanolic extract of R. communis was evaluated against Gram-negative bacteria E. coli and Klebsiella oxytoca. The agar well diffusion assay was used to determine the antibacterial activity. In the present study, we have shown experimentally that leaf extract of R. communis can induce the deterioration of the inner and outer cell membranes of E. coli and K. oxytoca and decrease their viability at a concentration of 50 mg/ml. Transmission electron microscopic results revealed cell membrane damage, cellular disintegration and release of cytoplasmic content, leading to cell death. To our knowledge, this is the first study of the antibacterial activity of R. communis against E. coli and K. oxytoca by Transmission electron microscopy. The ultramicroscopic observations showed that the phytochemical present in the leaf extract of R. communis could penetrate the bacterial cell, causing rupture of cell membranes and hence confirm the cytotoxic and antimicrobial property of R. communis.