Fungal jarosite biomineralization in Río Tinto.

Río Tinto is an extreme environment located at the core of the Iberian Pyrite Belt (IPB). It is an unusual ecosystem due to its size, constant acidic pH, high concentration of heavy metals and a high level of microbial diversity, mainly eukaryotic. Recently it was described the biomineralization of jarosite by Purpureocillium lilacinum, an acidic filamentous fungi isolated from the banks of the Tinto basin. In this study we further investigate the specificity of jarosite biomineralization by this fungi and its importance in the generation of jarosite in the Río Tinto basin. Our results clearly show that the ratio of the redox pairs and the Fe(3+) concentration is important to achieve a specific biomineralization of jarosite. The amount of nucleation sites also seems to be critical, although the presence of nucleation sites by itself is not sufficient to precipitate jarosite. There is a good correlation between the sampling sites along the river in which hydronium-jarosite has been identified and the presence of P. lilacinum.