Antibacterial and antifungal activities of silver, copper and zinc montmorillonites

The antibacterial and antifungal activity of montmorillonite, Ag-MMT, Cu-MMT and Zn-MMT were investigated. The antibacterial effects on Escherichia coli decreased in the order: Ag-MMT > Cu-MMT ≈ Zn-MMT. Free metal ions were active in a similar manner. The growth inhibition of Pycnoporus cinnabarinus decreased as Zn-MMT ≥ Cu-MMT > Ag-MMT and of Pleurotus ostreatus as Cu-MMT > Zn-MMT > Ag-MMT. Free metal ions inhibited the growth of the fungi in the same order. The antibacterial and antifungal effects of the MMTs were explained by interactions of released metal ions with the bacteria and fungi. Montmorillonite could serve as a suitable carrier of metal ions with antibacterial and antifungal properties.