Phosphate favors the biosynthesis of CdS quantum dots in Acidithiobacillus thiooxidans ATCC 19703 by improving metal uptake and tolerance

Giovanni Ulloa, Carolina P. Quezada, Mabel Araneda, Blanca Escobar, Edwar Fuentes, Sergio A. álvarez, Matías Castro, Nicolás Bruna, Rodrigo Espinoza-González, Denisse Bravo, José M. Pérez-Donoso

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Recently, we reported the production of Cadmium sulfide (CdS) fluorescent semiconductor nanoparticles (quantum dots, QDs) by acidophilic bacteria of the Acidithiobacillus genus. Here, we report that the addition of inorganic phosphate to Acidithiobacillus thiooxidans ATCC 19703 cultures favors the biosynthesis of CdS QDs at acidic conditions (pH 3.5). The effect of pH, phosphate and cadmium concentrations on QDs biosynthesis was studied by using Response Surface Methodology (RSM), a multivariate technique for analytical optimization scarcely used in microbiological studies to date. To address how phosphate affects intracellular biosynthesis of CdS QDs, the effect of inorganic phosphate on bacterial cadmium-uptake was evaluated. By measuring intracellular levels of cadmium we determined that phosphate influences the capacity of cells to incorporate this metal. A relation between cadmium tolerance and phosphate concentrations was also determined, suggesting that phosphate participates in the adaptation of bacteria to toxic levels of this metal. In addition, QDs-biosynthesis was also favored by the degradation of intracellular polyphosphates. Altogether, our results indicate that phosphate contributes to A. thiooxidans CdS QDs biosynthesis by influencing cadmium uptake and cadmium tolerance. These QDs may also be acting as a nucleation point for QDs formation at acidic pH. This is the first study reporting the effect of phosphates on QDs biosynthesis and describes a new cadmium-response pathway present in A. thiooxidans and most probably in other bacterial species.

Original languageEnglish
Article number234
JournalFrontiers in Microbiology
Volume9
Issue numberFEB
DOIs
Publication statusPublished - 20 Feb 2018

Keywords

  • Acid-stable quantum dots
  • Bioleaching bacteria
  • Nanoparticle biosynthesis
  • Phosphate
  • Quantum dots

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

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