Antibacterial activity of turmeric(Curcuma longa L)extract and effect on bacterial cell membranes
In the present study,the antibacterial spectrum of turmeric extract was analyzed by measuring the minimum inhibitory concentration(MIC),and the antibacterial mechanism of turmeric extract was elaborated by determining its effects on the permeability and integrity of the cytoplasmic membrane,energy metabolism,and the morphology of the tested bacteria(Bacillus subtilis)with the highest susceptibility to the extract.The results showed that turmeric extract possessed broad-spectrum antibacterial activity against Gram-positive,Gram-negative bacteria and fungi,especially against Bacillus subtilis,with the MIC of 0.5 mg·mL-1.Turmeric extract disrupted the liposome membrane and released calcein encapsulated within it.The permeability of the bacterial cell membrane was increased,leading to leakage of intracellular K+,Ca2+and cell wall proteins,and the integrity of the cell membrane was broken down,causing leakage of intracellular proteins and polysaccharides.Scanning electron microscope observation confirmed that the bacteria treated with turmeric extract was severely deformed.Simultaneously,cellular energy metabolism was affected,resulting in a significant reduction in the intracellular ATP content and ATPase activity in bacteria.In summary,the antibacterial mode of turmeric extract is closely related to its disruption of bacterial membrane structure.
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