A metagenomic and metabolomic analysis of an Ecuadorian mine tailings microbial community

Abstract

Mining produces an enormous quantity of waste material called tailings. Tailings are an environmental liability when they oxidize and produce acid mine drainage (AMD), but also contain residual metals with substantial economic value. Native microbial consortia catalyze AMD production by a factor of 106 over abiotic oxidation rates. These oxidative capabilities can be used in bioleaching heaps or stirred tank reactors to extract refractory metals from tailings and stabilize toxic heavy metals. Currently, bioleaching has unpredictable yields because both the microbes carrying out oxidation and accessory microbes are unidentified or poorly understood. The first portion of this project uses a metagenomic approach to identify key players in the Ecuador Tailings (ECT) community (including Acidithiobacillales, Bacillales, Capnodiales, Clostridiales, Eurotiales, Nitrospirales, and Thermoplasmatales) and their respective roles in iron- and sulfuroxidation pathways, quorum sensing, and cold- and heat-shock response. The second portion of the project developed methods for a metabolomic approach but did not produce data from ECT. Using complementary ‘omic’ approaches will allow broader understanding of key ECT organisms and help optimize bioleaching for maximum metal recovery.