Arsenic and Cadmium Bioremediation by Antarctic Bacteria Capable of Biosynthesizing CdS Fluorescent Nanoparticles

Use of microorganisms in contaminated water remediation is one of the most studied processes of recent years. The recovery of metal contaminants by converting them into high-value nanomaterials represents a scarcely explored topic with high potential economic impact. In this work, the authors determine the capacity to remove As and Cd from aqueous solutions by Antarctic bacteria previously reported as capable of biosynthesizing CdS fluorescent nanoparticles (NPs) at low temperatures. Bacterial characteristics favoring metal bioremediation, such as As and Cd resistance as well as high biofilm formation and metal removal (kinetic/sorption tests), were determined in Antarctic strains. In addition, the effect of As on the biosynthesis of CdS fluorescent NPs [quantum dots (QDs)] was evaluated. The presence of As inhibits the biosynthesis of CdS QDs by Antarctic bacteria. Arsenic inhibition does not involve the disruption of the Cd nanostructure or a decrease in H2S levels produced by cells, suggesting that As inhibits CdS biosynthesis by avoiding the interaction of Cd2+ with S2- required to produce the nanocrystal. Obtained results have significant consequences for the development of metal bioremediation strategies aimed at removing environmental heavy metals through the generation of NPs.