Copper removal ability by Streptomyces strains with dissimilar growth patterns and endowed with cupric reductase activity

ALBARRACÍN V. H.; AVILA, A. L.; AMOROSO M. J.; ABATE C.M.

Dalian, China

Simposio; 13th INTERNATIONAL BIOTECHNOLOGY SYMPOSIUM & EXHIBITION (IBS-2008); 2008

The potential use of metal resistant actinobacteria in bioremediation has been described before but little information is available about their copper resistance mechanisms. In a previous screening program, three copper resistant actinobacteria were isolated from polluted sediments of a drainage channel at Tucumán, Argentina. The aim of this work was to perform a phenotypic and genotypic characterization of these strains, and to study their growth behavior, copper retention ability and the presence of cupric reductase activity. Morphological, physiological and molecular  characterization of the resistant actinobacteria: AB2A, AB3 and AB5A, showed that they belonged to the Streptomyces genus. Strains were grown in Minimal Medium with 0.5mM of CuSO4 (MMCu) during seven days. Copper concentration in the supernatant was analyzed using a modified colorimetric technique with bicinchoninic acid reagent while growth was assessed by dry weight. The cupric-reductase assay was modified from a previously described method. All Streptomyces sp. strainswere able to remove copper from the MMCu while Streptomyces sp. AB5A, showed the best efficiency in copper removal (94%). Cupric-reductase activity (RACu) was detected in both, copper adapted cells and non-adapted cells of all three strains but this activity was up to 100-fold higher in pre-adapted cells of Streptomyces sp. AB2A. This is the first time that RACu  was demonstrated in Streptomyces strains.