Cupric reductase activity as part of the copper resistance mechanism in Amycolatopsis tucumanensis

JOSÉ DÁVILA COSTA; VIRGINIA H. ALBARRACÍN; CARLOS M. ABATE

San Miguel de Tucumán, Argentina

Congreso; XLV Reunión Anual de la (SAIB); 2009

Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular

Amycolatopsis tucumanensis DSM 45259T, isolated from copper polluted sediments, has been studied for its remarkable copper resistance as well as for its high bioaccumulation abilities. Nevertheless, there is no specific information about proteins involved in the copper resistance mechanisms in actinobacteria. The aim of this work was to studied the cupric reductase activity of this novel strain as part of its copper resistance mechanisms. The strains under studied were A. tucumanensis DSM 45259T and Streptomyces sp. AB5A and as sensitive controls, Streptomyces coelicolor DSM 40783T and Amycolatopsis eurytherma DSM 44348T. Strains were grown in Minimal Medium (agar or broth) with 0.25, 0.5 and 1 mM of CuSO4 (MMCu) during four days. Cupric-reductase activity (RACu) under different incubation temperatures (10, 25, 30, 45 ºC) were analyzed using a modified colorimetric technique with bicinchoninic acid reagent while growth was assessed by dry weight.  The highest RACu was detected in A. tucumanensis (220 mU/mg of cells), which also was the most copper resistant strain of all selected as it was able to grow in the maximal copper concentration tested (1 mM). Cupric-reductase activity was detected in both, copper adapted cells and non adapted cells of all strains but this activity was up to 4-fold higher in pre-adapted cells of DSM 45259T. This is the first time that RACu was demonstrated in Amycolatopsis strains.