Microorganisms Accelerate REE Mineralization in Supergene Environments

Metabarcoding reveals ecologically distinct fungal assemblages in river and groundwater along an Austrian alpine to lowland gradient

Biodiversity, the source of origin, and ecological roles of fungi in groundwater are to this day a largely neglected field in fungal and freshwater ecology. We used DNA-based Illumina high-throughput sequence analysis of both fungal gene markers 5.8S and internal transcribed spacers region 2 (ITS2), improving taxonomic classification. This study focused on the groundwater and river mycobiome along an altitudinal and longitudinal transect of a pre-alpine valley in Austria in two seasons. Using Bayesian network modeling approaches, we identified patterns in fungal community assemblages that were mostly shaped by differences in landscape (climatic, topological, and geological) and environmental conditions. While river fungi were comparatively more diverse, unique fungal assemblages could be recovered from groundwater, including typical aquatic lineages such as Rozellomycota and Olpidiomycota. The most specious assemblages in groundwater were not linked to the input of organic material from the surface, and as such, seem to be sustained by characteristic groundwater conditions. Based on what is known from closely related fungi, our results suggest that the present fungal communities potentially contribute to mineral weathering, carbon cycling, and denitrification in groundwater. Furthermore, we were able to observe the effects of varying land cover due to agricultural practices on fungal biodiversity in groundwater ecosystems. This study contributes to improving our understanding of fungi in the subsurface aquatic biogeosphere.

Various microbes used for the recovery of rare earth elements from mine wastewater

Microbes used for the recovery of rare earth elements (REEs) from mining wastewater indicated traces of Escherichia coli (E. coli, 2149.6 μg/g), Bacillus sphaericus (1636.6 μg/g), Bacillus mycoides (1469.3 μg/g), and Bacillus cereus (1083.9 μg/g). Of these, E. coli showed an affinity for REEs than non-REEs (Mn and Zn). The amount of heavy REEs adsorbed (1511.1 μg/g) on E. coli was higher than light REEs (638.0 μg/g) due to the process of increasing adsorption with decreasing ionic radius. Additionally, E. coli demonstrated stability in the recovery of REEs from mining wastewater, as evidenced by 4 cycles. SEM-EDS, XPS and FTIR showed that REEs had a disruptive effect on cells, REEs absorbed and desorbed on the cell surface including ion exchange with ions such as Na+, ligand binding with functional groups like -NH2. Finally, the cost assessment confirmed the economically feasible of E. coli in recovery of REEs from mining wastewater.

Response of bacterial ecological and functional properties to anthropogenic interventions during maturation of mine sand soil

Soil formation is a complex process that starts from the biological development. The ecological principles and biological function in soil are of great importance, whereas their response to anthropogenic intervention has been poorly understood. In this study, a 150-day microcosmic experiment was conducted with the addition of sludge and/or fermented wood chips (FWC) to promote the soil maturation. The results showed that, compared to the control (natural development without anthropogenic intervention), sludge, FWC, and their combination increased the availability of carbon, nitrogen, and potassium, and promoted the soil aggregation. They also enhanced the cellulase activity, microbial biomass carbon (MBC) and bacterial diversity, indicating that anthropogenic interventions promoted the maturation of sand soil. Molecular ecology network and functional analyses indicated that soil maturation was accomplished with the enhancement of ecosystem functionality and stability. Specifically, sludge promoted a transition in bacterial community function from denitrification to nitrification, facilitated the degradation of easily degradable organic matter, and enhanced the autotrophic nutritional mode. FWC facilitated the transition of bacterial function from denitrification to ammonification, promoted the degradation of recalcitrant organic matter, and simultaneously enhanced both autotrophic and heterotrophic nutritional modes. Although both sludge and FWC promoted the soil functionality, they showed distinct mechanistic actions, with sludge enhancing the physical structure, and FWC altering chemical composition. It is also worth emphasizing that sludge and FWC exhibited a synergistic effect in promoting biological development and ecosystem stability, thereby providing an effective avenue for soil maturation.

High-efficiency dysprosium-ion extraction enabled by a biomimetic nanofluidic channel

Biological ion channels exhibit high selectivity and permeability of ions because of their asymmetrical pore structures and surface chemistries. Here, we demonstrate a biomimetic nanofluidic channel (BNC) with an asymmetrical structure and glycyl-L-proline (GLP) -functionalization for ultrafast, selective, and unidirectional Dy3+ extraction over other lanthanide (Ln3+) ions with very similar electronic configurations. The selective extraction mainly depends on the amplified chemical affinity differences between the Ln3+ ions and GLPs in nanoconfinement. In particular, the conductivities of Ln3+ ions across the BNC even reach up to two orders of magnitude higher than in a bulk solution, and a high Dy3+/Nd3+ selectivity of approximately 60 could be achieved. The designed BNC can effectively extract Dy3+ ions with ultralow concentrations and thereby purify Nd3+ ions to an ultimate content of 99.8 wt.%, which contribute to the recycling of rare earth resources and environmental protection. Theoretical simulations reveal that the BNC preferentially binds to Dy3+ ion due to its highest affinity among Ln3+ ions in nanoconfinement, which attributes to the coupling of ion radius and coordination matching. These findings suggest that BNC-based ion selectivity system provides alternative routes to achieving highly efficient lanthanide separation.

Enhancing La(III) biosorption and biomineralization with Micromonospora saelicesensis: Involvement of phosphorus and formation of monazite nano-minerals

The release of rare earth elements (REEs) from mining wastes and their applications has significant environmental implications, necessitating the development of effective prevention and reclamation strategies. The mobility of REEs in groundwater due to microorganisms has garnered considerable attention. In this study, a La(III) resistant actinobacterium, Micromonospora saelicesensis KLBMP 9669, was isolated from REE enrichment soil in GuiZhou, China, and evaluated for its ability to adsorb and biomineralize La(III). The findings demonstrated that M. saelicesensis KLBMP 9669 immobilized La(III) through the physical and chemical interactions, with immobilization being influenced by the initial La(III) concentration, biomass, and pH. The adsorption kinetics followed a pseudo-second-order rate model, and the adsorption isotherm conformed to the Langmuir model. La(III) adsorption capacity of this strain was 90 mg/g, and removal rate was 94 %. Scanning electron microscope (SEM) coupled with energy dispersive X-ray spectrometer (EDS) analysis revealed the coexistence of La(III) with C, N, O, and P. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) investigations further indicated that carboxyl, amino, carbonyl, and phosphate groups on the mycelial surface may participate in lanthanum adsorption. Transmission electron microscopy (TEM) revealed that La(III) accumulation throughout the M. saelicesensis KLBMP 9669, with some granular deposits on the mycelial surface. Selected area electron diffraction (SAED) confirmed the presence of LaPO4 crystals on the M. saelicesensis KLBMP 9669 biomass after a prolonged period of La(III) accumulation. This post-sorption nano-crystallization on the M. saelicesensis KLBMP 9669 mycelial surface is expected to play a crucial role in limiting the bioimmobilization of REEs in geological repositories.