Background:
The effects of exposure to copper, during growth, on the production of biomass, total protein,
catalase, glutathione-S transferase, glutathione peroxidase, peroxidase, polyphosphate, acid and alkaline
phosphatases, ultrastructure and the ability to remove this metal from
Aspergillus niger
, obtained from caatinga
soil, were evaluated.
Results:
All parameters testedwere influenced by the concentration of metal in the culturemedium. The presence
of metal induced high levels of antioxidant enzymes, including lipid peroxidation, thereby revealing the
appearance of an oxidative stress response. The variation in polyphosphate levels indicates the participation of
the polymer in response to stress induced by copper. The activities of the phosphatases were positively
influenced by growing them in the presence of copper. Ultrastructure changes in the cell surface, electron
density, thickness, and septation were visualized by exposing cells to increasingly larger concentrations of
metal. The isolate was able to remove the agent from the growth medium, while maintaining its physiological
functions. The metal removed from the cultures exposed to 0.5 mM, 1 mM and 2 mM copper exhibited
percentages of removal equivalent to 75.78%, 66.04% and 33.51%.
Conclusions:
The results indicate that the isolate was able to grow in high concentrations of copper, activates
mechanisms for adaptation and tolerance in the presence of metal, and is highly efficient at removing the
agent. Such data are fundamental if a better understanding is to be reached of the cellular and molecular
abilities of native isolates, which can be used to develop bioprocesses in environmental and industrial areas.
