Copper tolerant yeasts isolated from polluted area of Argentina

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

JOURNAL OF BASIC MICROBIOLOGY

WILEY-V C H VERLAG GMBH

Año: 2005 vol. 45 p. 381 - 391

0233-111X

Eleven yeasts were isolated from wastewater sediment samples collected from a copper filter mine plant, located in Tucumán province, Argentina. Amongst them, two isolates designated as RCL-3 and RCL-11 were selected based on their multiple tolerances to different heavy metals and studied their biosorption capacity to copper. Growth performance and copper toxicity by the two yeasts were evaluated using YNB-glucose medium supplemented with 0.1, 0.2, 0.5 and 1 mM of Cu2+ solutions. RCL-3 was able to grow up to 7 mg ml-1 biomass in the presence of either 0.1 or 0.2 mM Cu2+, and at 0.5 mM Cu2+ growth reached 5.5 mg ml-1. However RCL-11 isolated yeast reached 8 mg ml-1 in the presence of 0.1 mM Cu2+. Values of 6.5 and 5.5 mg ml-1 biomass were obtained at 0.2 and 0.5 mM Cu2+respectively. Intra and extracellular copper biosorption kinetic of RCL-3 and RCL-11 was evaluated. After adding 0.1, 0.2, and 0.5 mM to the cultures, the intracellular copper concentration increased to 0.09 and 0.06 mM for RCL-3 and RCL-11, respectively. However, the copper accumulation profiles were different: the metal was librated outside the cells by RCL-3 whereas RCL-11 kept it inside the cell. Specific biosorption of copper by both yeasts showed that the biosorption increased with the initial copper fed in the medium (11.5 and 8.0 mg Cu g biomass-1 for RCL-3 and RCL-11, respectively). However specific biosorption diminution values were observed along with the time. Key words: yeasts, copper, biosorption