Iberian Pyrite Belt Subsurface Life (IPBSL), a Drilling Project of Biohydrometallurgical Interest

Abstract

The geomicrobiological characterization of Río Tinto, an extreme acidic environment, has proven the importance of the iron cycle, not only in generating the extreme conditions of the habitat (low pH, high concentration of toxic heavy metals) but also in maintaining the high level of microbial diversity detected in the water column and the sediments. The extreme conditions detected in the Tinto basin are not the product of industrial contamination but the consequence of the presence of an underground bioreactor that obtains its energy from the massive sulfide minerals of the Iberian Pyrite Belt (IPB). To test this hypothesis, a drilling project (IPBSL) to intersect ground waters interacting with the mineral ore is under way, to provide evidence of subsurface microbial activities. A dedicated geophysical characterization of the area selected two drilling sites due to the possible existence of water with high ionic content. Two wells have been drilled in Peña de Hierro, BH11 and BH10, with depths of 340 and 630 meters respectively, with recovery of cores and generation of samples in anaerobic and sterile conditions. The geological analysis of the retrieved cores showed an important alteration of mineral structures associated with the presence of water, with production of expected products from the bacterial oxidation of pyrite. Ion chromatography of water soluble compounds from uncontaminated samples showed the existence of putative electron donors, electron acceptors, as well as variable concentration of metabolic organic acids, which suggest the presence of an active subsurface ecosystem associated to the high sulfidic mineral content of the IPB. Enrichment cultures from selected samples showed evidences of an active iron and sulfur cycle, together with unexpected methanogenic, methanotrophic and acetogenic activities. The geological, geomicrobiological and molecular biology analyses which are under way, should allow the characterization of this ecosystem of biohydrometallurgical interest

Study of methanogenic enrichment cultures of rock cores from the deep subsurface of the Iberian Pyritic Belt

“…In this campaign two deeper boreholes were drilled, BH11 (320 m) and BH10 (620 m). Similarly to the previous study, analysis of rock samples indicated the presence of gases such as hydrogen, carbon dioxide and methane as well as anions such as the nitrate, nitrite, acetate, formate and propionate were detected within BH10 and BH11 boreholes ( Amils et al., 2013 ). To address microbial diversity and establish a real understanding of the microbial community interaction with the local geology, rock core samples from 39 depths on BH10 and 20 depths on BH11 were sampled under anaerobic and sterile conditions.…”

Nucleation of Fe-rich phosphates and carbonates on microbial cells and exopolymeric substances

“…It was isolated from a 297 m depth-drilling core obtained from the Iberian Pyrite Belt (Puente-Sánchez et al, 2014a ). Only the innermost part of the core was sampled, and sodium bromide was added to the drilling water as a tracer for potential contamination, as described in Amils et al ( 2013 ).…”

Draft Genome Sequence of Shewanella sp. Strain T2.3D-1.1, Isolated from 121.8 Meters Deep in the Subsurface of the Iberian Pyrite Belt

“…Shewanella sp. strain T2.3D-1.1 was isolated from a strictly anaerobic denitrification enrichment culture using a 121.8-m-deep core sample obtained from a drilling project aimed at studying the microbial diversity existing in the deep subsurface of the Iberian Pyrite Belt (southwest Spain) ( 2 ). The borehole coordinates were 37°43′45.42″N and 6°33′23.57″W.…”