Cr (VI) or Cu (II) removal by indigenous yeasts isolated from Argentinean polluted sites

VILLEGAS L B; J. RIVADENEIRA; O. DELGADO; M. J. AMOROSO; L. I. C. DE FIGUEROA

Rio de Janeiro- Brasil

Conferencia; 11th Internacional Congress on Yeasts; 2004

Heavy metal pollution is one the most serius environmntal problems. Mining and industrial activity are the main sources of heavy metal contamination. Iron, Zinc, Nickel, Chromium and Cupper play an important role as trace elements in biochemical reactions but these heavy metal ions are toxic at higher concentrations, producing serius public health problems.Traditional technologies for the removal of these heavy metals are very expensive and may have several disadvantages. New techniques like biosorption, are required for reducing their concentrations to environmentally acceptable levels at low costs.Microorganisms possess a potential for accumulating or removing many heavy metal cations and they are the most inexpensive source of biomass. The aim of theis work was to study yeast strains capable to uptake Cu2+ or Cr6+. Soil and water samples were collected from different contaminated sites where with mine and tannery factories dischange tehir effluents containing Cu2+ or Cr6+ respectively. These microorganisms were cultured in minimal medium containing 0.1 to 1 mM Cu2+ or Cr6, cultures without the addition of heavy metals were performed as controls. The growth was followed by turbidity measurements at O.D. 620 nm and by dry wight. Heavy metals concentrations were determined intracellularly and in free cell supernatants by both, atomic absorption spectrophotmeter and colorimetric methods. The growth rates and the heavy metals uptake decreased when the initial Cu2+ and Cr6+ concentrations in the medium were increased. The islates were grouped using the RFLP restriction patterns from the ribosimal region. These results play an important role for understanding how these microorganisms develp resitance mechanisms for heavy metals when they are in toxic concentraions.   Acknowledgements: Dr.Orlando Villegas for atomic absorption spectrophotometer determinate of San Luis University, Argentina.