Mining is a very important industry worldwide; however, environmental and human health damages associated to this activity constitute one of the most complex current environmental problems (Ochoa, 2013). Various types of contaminated
effluents are generated during mining extraction, one of them being acid mine drains (DAM) that are characterized by high acidity, high content of dissolved heavy metals and high concentrations of sulfate ions. These effluents generate environmental problems due to their high potential for contamination of surface and / or underground water resources and are known for being difficult to treat with conventional physical-chemical remediation techniques (Ferreira, 2006). In this context, the development of new technologies for the treatment of AMD, based on bioreactors packed with local sulfatereducing bacteria (BSR), becomes a priority in the country; not only for the legislation and policies in force for the protection of the environment and public health, but also for the control that was intensified with the approval of the Mining Law. The application of molecular techniques in the bioremediation processes of contaminated effluents is of great importance since it provides information on the microbial diversity present and allows determining the populations involved in the treatment of DAM. Many of these molecular techniques are based on the amplification of specific sequences of certain microorganisms, such as pyrosequencing, whose objective is to obtain information on the function and performance of dominant populations and probably responsible for bioremediation processes (Wesley, 2006). This is the case of sulfatereducing bacteria to which DAM treatment is attributed.
The vast majority of environmental microorganisms are hardly cultivable with conventional culture techniques, which limits the possibility of exploring their genetic diversity (Gibson, 2008). This is especially problematic in complex matrices such as soils or sediments that are characterized by an extraordinary microbial diversity; that is why molecular methods based on the determination of large-scale DNA sequences, applicable to complete genomes, have been instrumental in overcoming these limitations. The possibility of automating and parallelizing the sequencing process offered by this technique is one of the main advantages over other sequencing methods. Pyrosequencing allows the sequencing of large amounts of DNA in less time than other techniques and at a lower cost in relation to the results obtained (McKnight, 2004).
In view of the great mining problema that Ecuador faces, specifically in the southern region of the country where the consequences left by mining activity are visible both in the physical environment and in the quality of life of the inhabitants of the sector (Andrade, 2010); the characterization of the bacterial diversity responsible for the treatment of DAM will provide important genetic information that can be used to develop local technologies for remediation of mining effluents based on the use of endogenous microbial consortia (Wesley, 2006).
Finally, this type of studies will contribute to educating the population on environmental issues as important as environmental protection and the development of technologies for the treatment of mining effluents.