High Copper Tolerant <i>P. lilacinum</i> Strain Isolated from a Rich Environment in Copper, Río Tinto (Sw, Spain)

Abstract

Río Tinto (Southwestern Spain, Iberian Pyrite Belt) is an unusual extreme environment with an unexpected level of eukaryotic microbial diversity. Of the different fungal strains isolated along the river over several years, one of them,Purpureocillium lilacinumM15001, is able to tolerate up to 1M Cu concentrations. This strain was able to remove 25% of the Cu when incubated at 50mM, 32% at 100mM and 51% at 500mM Cu concentrations. The amount of Cu detected inside the cells increased accordingly the concentration of Cu in the solution, from 8.2% of the total fungal dry weight at 50mM Cu concentration, to 13% when exposed to 100mM Cu and 22.4% at 500mM Cu. TEM studies showed the existence of electrodense material externally adsorbed to the fungal cell wall, as well as large intracellular deposits. EDX microanalyses revealed that this material was composed mainly of Cu. To clarify the possible resistance mechanisms involved in the tolerance of this fungal strain to Cu, a proteomic study has been carried out.