Electronic scraps (e‐scraps) represent an attractive raw material to mine demanded metals, as well as rare earth elements (REEs). A sequential microbial‐mediated process developed in two steps was examined to recover multiple elements. First, we made use of an acidophilic bacteria consortium, mainly composed of Acidiphilium multivorum and Leptospidillum ferriphilum, isolated from acid mine drainages. The consortium was inoculated in a dissolution of e‐scraps powder and cultured for 15 days. Forty‐five elements were analyzed in the liquid phase over time, including silver, gold, and 15 REEs. The bioleaching efficiencies of the consortium were >99% for Cu, Co, Al, and Zn, 53% for Cd, and around 10% for Cr and Li on Day 7. The second step consisted of a microalgae‐mediated uptake from e‐scraps leachate. The strains used were two acidophilic extremotolerant microalgae, Euglena sp. (EugVP) and Chlamydomonas sp. (ChlSG) strains, isolated from the same extreme environment. Up to 7.3, 4.1, 1.3, and 0.7 µg by wet biomass (WB) of Zn, Al, Cu, and Mn, respectively, were uptaken by ChlSG biomass in 12 days, presenting higher efficiency than EugVP. Concerning REEs, ChlSG biouptake 14.9, 20.3, 13.7, 8.3 ng of Gd, Pr, Ce, La per WB. Meanwhile, EugVP captured 1.1, 1.5, 1.4, and 7.5, respectively. This paper shows the potential of a microbial sequential process to revalorize e‐scraps and recover metals and REEs, harnessing extremotolerant microorganisms.

The extraction and processing of uranium (U) have polluted large areas worldwide, rendering anthropogenic extreme environments inhospitable to most species. Noticeably, these sites are of great interest for taxonomical and applied bioprospection of extremotolerant species successfully adapted to U tailings contamination. As an example, in this work we have studied a microalgae species that inhabits extreme U tailings ponds at the Saelices mining site (Salamanca, Spain), characterized as acidic (pH between 3 and 4), radioactive (around 4 μSv h⁻¹) and contaminated with metals, mainly U (from 25 to 48 mg L⁻¹) and zinc (from 17 to 87 mg L⁻¹). After isolation of the extremotolerant ChlSP strain, morphological characterization and internal transcribed spacer (ITS)-5.8S gene sequences placed it in the Chlamydomonadaceae, but BLAST analyses identity values, against the nucleotide datasets at the NCBI database, were very low (<92%). We subjected the ChlSP strain to an artificial selection protocol to increase the U uptake and investigated its response to selection. The ancestral strain ChlSP showed a U-uptake capacity of ≈4.30 mg U g⁻¹ of dry biomass (DB). However, the artificially selected strain ChlSG was able to take up a total of ≈6.34 mg U g⁻¹ DB, close to the theoretical maximum response (≈7.9 mg U g⁻¹ DB). The selected ChlSG strain showed two possible U-uptake mechanisms: the greatest proportion by biosorption onto cell walls (ca. 90%), and only a very small quantity, ~0.46 mg g⁻¹ DB, irreversibly bound by bioaccumulation. Additionally, the kinetics of the U-uptake process were characterized during a microalgae growth curve; ChlSG cells removed close to 4 mg L⁻¹ of U in 24 days. These findings open up promising prospects for sustainable management of U tailings waters based on newly evolved extremotolerants and outline the potential of artificial selection in the improvement of desired features in microalgae by experimental adaptation and selection.

Global warming represents a challenge to the survival of phytoplankton organisms, which are the basis of the aquatic food web and drive essential biogeochemical cycles. We propose a direct experimental research mimicking temperature-increasing scenarios as a novel way to explore the adaptation of phytoplankton to predicted future thermal scenarios. This vulnerability analysis of individual phytoplankton species to increased temperature is key to understand the impact of global warming on aquatic ecosystems. Considering the polyphyletic complexity of the phytoplankton community, we compare the adaptation ability of diverse phytoplankton species from oceanic, coastal and inland waters to global warming, evaluating the role played by physiological acclimatization and genetic adaptation. We found that physiological acclimatization allows survival under the lowest temperature increase. Afterwards pre-existing genetic variability allow some genotypes to survive. Finally, when the temperature rises to a certain threshold, only the occurrence of new mutations that confer thermal resistance assures adaptation. Our results also reveal diverse degrees of tolerance to temperature increase among the different functional groups of phytoplankton, with great inter-specific capacity for genetic adaptation.