Seleção de leveduras com potencial uso em processos de biorremediação e avaliação fisiológica do impacto de elementos traço nas células

Abstract

In the last thirty years the expansion of industrial sectors, e specially metallurgy and mining, revealed a progressive increase in the generation of toxic waste. So, the management of this waste, in order to minimize the pollution generated by them, has been a global concern. It is known that microorganisms have a high capacity to absorb these trace elements. The yeast Pichia kudriavzevii was previously selected and used in bioaugmentation experiments (microcosms) with soil artificially contaminated with Cd, Zn and Pb. The results demonstrated that Pichia kudriavzevii CCMA 0136 was able to reduce the availability of the trace elements when evaluated in soil extract 37% of Cd, Zn 16% and Pb 48% and non-viable cells that are most efficient when compared with the feasible. This study found that when exposed to P. kudriavzevii mixture of metals (Cd, Pb and Zn) after 6 hours, maintaining the integrity of the membrane, but shows the loss of metabolic activity and proliferation capacity and Pb was responsible for the effects toxic caused in the cell. Oxidative stress after exposure to yeast multimetais seems to be responsible for the disruption of the plasma membrane, once the trigger of membrane integrity loss coincided with the accumulation of ROS. Also the Pb element was responsible for the accumulation of internal ROS. The presence of glucose increased the loss of membrane integrity and proliferation capacity induced by trace elements. Sodium azide alleviates toxicity of trace elements on the cells, but the Ca ions were not able to protect the toxicity generated by Cd and Pb. This information may be useful in the use of P. kudriavzevii in soil bioremediation and soil leachate adduced with trace elements.