Searching for antimony-recycler microorganisms in Arctic mine waste

Mining activities generate waste material, which can result in the release of metals and metalloids to ecosystems. Although metal(loid)s in waste materials may potentially be valuable resources, when those pollutants end up in nature, they can have negative effects on the organisms inhabiting those sites. Some microorganisms with the ability to tolerate metal(loid)s can colonize and inhabit highly contaminated places by using strategies such as specialized metabolic pathways or resistance mechanisms. Because of the ability of certain microbes to transform metal(loid)s, there is interest in studying microbial communities from mining contaminated sites and their potential industrial applications, such as bioremediation. However, there are still many gaps to fill in the knowledge of microbes from polluted places and their interactions with elements in nature, especially in extreme places, such as the Arctic. In the mining areas in our study, antimony (Sb) is of particular interest. Antimony is an element that has been listed as a priority pollutant internationally and a critical raw material for the EU. Mining operations contribute to the release of Sb to surrounding native areas and efforts are needed to remove antimony from mining sites to reduce the environmental contamination and to develop alternative sources of Sb from mine waste. Different approaches have been described for Sb bioremediation, like antimonate (Sb(V)) reduction and subsequent precipitation. However, only a few Sb(V)-reducing microorganisms have been reported.

The main goal of the presented doctoral thesis was to study microorganisms that utilize Sb as part of their Sb(V)-reductive metabolism to test their ability to immobilize antimony from artificial mine water. The objectives consisted of: the assessment of microbial communities from different Arctic mine environments (i); the enrichment, isolation and characterization of putative Sb(V)-respiring microorganisms from Arctic mine sites (ii); a study of the genetic expression of Sb(V)-respiring bacteria (iii); testing of the applicability of (sub)-arctic microorganisms for Sb recovery (iv) and share research findings through scientific communication (v). The presented thesis will contribute to the knowledge of metal(loid)-metabolizing microorganisms from mine sites, providing new tools for solving environmental challenges in the Arctic.