Anti-Fungal Activity of Copper

Copper as an anti-fungal surface agent

Although less research has been carried out on antifungal activity of copper it is unanimously accepted that an activity similar to that described for bacterial species exists in fungus.

Quaranta et al. (2011) investigated the mechanism of ‘contact killing’ in Candida albicans and yeast Saccharomyces cerevisiae cells in contact with copper coupons (C11000 99·9% Cu and C75200 62% Cu) (Quaranta et al. 2011). The modification of copper homeostasis caused four to six times faster killing of C. albicans lacking copper-ATPase export and S. cerevisiae deficient for copper uptake transporters, both involved in the intracellular regulation of copper, than of wild-type cells due to an intracellular accumulation of copper. The authors showed that the first damages were localized on membranes, similar to the bacterial mechanism of ‘contact killing’. In addition, mutation detection assays showed the complete absence of DNA damage. The Live/Dead staining assay confirmed this hypothesis by showing rapid and extensive cytoplasmic membrane damage after yeast exposure to copper surfaces.

However, in C. albicans strains, which express higher levels of the CRP1 P1-type ATPase copper transporter gene, the resistance against copper is greater by regulating the intracellular uptake of copper. ALS1 and ALS3, a cluster of genes encoding cell surface-associated glycoproteins, could regulate CRP1 and de facto suggest a different resistance mechanism from ‘contact killing’ (Zheng et al. 2016).

Copper as an antifungal particle agent

As in bacteria, the Cu-NPs have a potent antifungal activity. Ghasemian et al. (2012) tested antifungal activity against filamentous fungi such as Alternaria alternata, Aspergillus flavus, Fusarium solani and Penicillium chrysogenum. They synthesized 8 nm Cu-NPs and showed an important antifungal activity of these particles with minimal inhibitory concentrations (MIC) ranging from 40 to 80 mg l⁻¹ (Ghasemian et al. 2012) and that particle size is an important factor in the antimicrobial activity of copper. Other studies have reported the antifungal activity of Cu-NPs against Candida species (Usman et al. 2013; Kruk et al. 2015).