Effects of lemongrass oil on the morphological characteristics and peptidoglycan synthesis of Escherichia coli cells.

Abstract

The antibacterial effect of lemongrass oil, obtained from the aerial part of Cymbopogon citratus, on cells of Escherichia coli was investigated by electron microscopy and by measuring cell wall formation. Two strains of E. coli K-12 were used, one of which required diaminopimelic acid in the growth medium for its murein formation. Lemongrass oil was found to elicit morphological changes like filamentation, inhibition of septum formation, spheroplast formation, production of 'blisters', 'bulges' or mesosomes, as well as lysis and development of abnormally shaped cells. The incorporation of radioactively labelled diaminopimelic acid into the cell wall murein of strain W7, was inhibited by lemongrass oil in a dose dependent way. The sequence of changes induced by lemongrass oil on bacterial cell morphology and also its interference with murein synthesis in E. coli cells were interpreted to involve the penicillin binding proteins PBP 2 and PBP 3.