Biomineralization and biosynthesis of nanocrystalline materials and selective uptake of toxic metals controlled by five types of Candida species

Abstract

The use of microorganisms for in vivo synthesis of quantum dots (QDs) not only makes it possible to obtain useful materials with tunable characteristics under mild conditions, but can also ensure the removal of toxic heavy metals from polluted water systems. Because real water treatment schemes contain more than one pollutant, this work attempted to determine the responses of Candida to exposure to two cations with known different survival pathways: Pb(II) and Cd(II). Five Candida species, C. albicans, C. dubliniensis, C. glabrata, C. krusei, and C. parapsilosis, were exposed to a 1 : 1 mixture of the aforementioned cations. The heterogeneous uptake of each metal was defined for the different strains; the removal of cadmium was greater than that of lead. The specific pathway followed by each cation led to the biomineralization of heterogeneous PbS- and CdS-based QDs located extra- or intra-cellularly. The structures and properties of the obtained heterogeneous nanomaterials were characterized by different techniques, and the results highlight the potential of Candida to form useful materials from a complex metal mixture.