Evidence of microalgal isotopic fractionation through enrichment of depleted uranium

An exploratory study on the possibilities of microalgal biotechnology to obtain the essential 6Li isotope as fusion fuel

Future energy supply needs to overcome two challenges: environmental impact and dependence on geopolitically unstable countries. A very promising alternative is based on lithium, an element for batteries, and whose isotope 6Li will be essential in nuclear fusion. The objective of this research has been to determine if it is possible to achieve isotopic fractionation of lithium through a process mediated by microalgae. For this purpose, Chlamydomonas reinhardtii was selected and grown in presence of 5 mg/L of lithium. Results revealed that this specie survives at the selected lithium concentration, discriminates isotopes and preferentially capture 6Li (6δ = 10.029 ± 3.307) through a process independent of the cellular growth. Concomitate recovered up 0.206 mg/L of lithium along a process of 21 days. The result of this study lets to affirm that Chlamydomonas reinhardtii might be used to obtain lithium enriched in the lighter isotope.

Functionalized hierarchically porous carbon doped boron nitride for multipurpose and efficient treatment of radioactive sewage

In order to recycle Uranium (U) for the sustainable development of nuclear energy, diamide bipyridine (DABP) modified hierarchically porous carbon doped boron nitride (BCN-DABP) was synthesized as an adsorbent for the multipurpose removal of U. BCN-DABP displayed good adsorption performance for U in both weakly and highly acidic solutions. The hierarchically porous structure endowed BCN-DABP with ultrafast adsorption kinetics, and adsorption reached equilibrium within 180.0 and 0.5 min under pH = 4.0 and 2.00 mol L^-1 HNO₃, respectively. Moreover, combination of adsorption isotherm studies and DFT calculations showed that BCN-DABP possessed high adsorption capacities for U and displayed different adsorption performance under different conditions. BCN-DABP adsorbed UO₂²⁺ by chelation and electrostatic attraction under pH 4.0 and 2.00 mol L^-1 HNO₃, the maximum adsorption capacity under two conditions reached 818.7 and 1296.7 mg g^-1, respectively. As a result, BCN-DABP is expected to be used for the rapid and efficient removal of U in various kinds of contaminated water. Furthermore, excellent salinity tolerance, good adsorption selectivity, and outstanding radiation resistance also endowed BCN-DABP with great practical potential for removing U in radioactive contaminated water as well as high level liquid waste.

Microbial biominers: Sequential bioleaching and biouptake of metals from electronic scraps

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.

Dual-Use Quickscan: A Web-Based Tool to Assess the Dual-Use Potential of Life Science Research

Research on pathogenic organisms is crucial for medical, biological and agricultural developments. However, biological agents as well as associated knowledge and techniques, can also be misused, for example for the development of biological weapons. Potential malicious use of well-intended research, referred to as “dual-use research”, poses a threat to public health and the environment. There are various international resources providing frameworks to assess dual-use potential of the research concerned. However, concrete instructions for researchers on how to perform a dual-use risk assessment is largely lacking. The international need for practical dual-use monitoring and risk assessment instructions, in addition to the need to raise awareness among scientists about potential dual-use aspects of their research has been identified over the last years by the Netherlands Biosecurity Office, through consulting national and international biorisk stakeholders. We identified that Biorisk Management Advisors and researchers need a practical tool to facilitate a dual-use assessment on their specific research. Therefore, the Netherlands Biosecurity Office developed a web-based Dual-Use Quickscan (www.dualusequickscan.com), that can be used periodically by researchers working with microorganisms to assess potential dual-use risks of their research by answering a set of fifteen yes/no questions. The questions for the tool were extracted from existing international open resources, and categorized into three themes: characteristics of the biological agent, knowledge and technology about the biological agent, and consequences of misuse. The results of the Quickscan provide the researcher with an indication of the dual-use potential of the research and can be used as a basis for further discussions with a Biorisk Management Advisor. The Dual-Use Quickscan can be embedded in a broader system of biosafety and biosecurity that includes dual-use monitoring and awareness within organizations. Increased international attention to examine pathogens with pandemic potential has been enhanced by the current COVID-19 pandemic, hence monitoring of dual-use potential urgently needs to be encouraged.

The Upcoming 6Li Isotope Requirements Might Be Supplied by a Microalgal Enrichment Process

Lithium isotopes are essential for nuclear energy, but new enrichment methods are required. In this study, we considered biotechnology as a possibility. We assessed the Li fractionation capabilities of three Chlorophyte strains: Chlamydomonas reinhardtii, Tetraselmis mediterranea, and a freshwater Chlorophyte, Desmodesmus sp. These species were cultured in Li containing media and were analysed just after inoculation and after 3, 12, and 27 days. Li mass was determined using a Inductively Coupled Plasma Mass Spectrometer, and the isotope compositions were measured on a Thermo Element XR Inductively Coupled Plasma Mass Spectrometer. The maximum Li capture was observed at day 27 with C. reinhardtii (31.66 µg/g). Desmodesmus sp. reached the greatest Li fractionation, (δ⁶ = 85.4‰). All strains fractionated preferentially towards ⁶Li. More studies are required to find fitter species and to establish the optimal conditions for Li capture and fractionation. Nevertheless, this is the first step for a microalgal nuclear biotechnology.

Biosorption of Uranyl Ions from Aqueous Solution by Parachlorella sp. AA1

In the present study we investigated the ability of the microalgal strain Parachlorella sp. AA1 to biologically uptake a radionuclide waste material. Batch experiments were conducted to investigate the biosorption of uranyl ions (U(VI)) in the 0.5–50.0 mg/L concentration range by strain AA1. The results showed that AA1 biomass could uptake U(VI). The highest removal efficiency and biosorption capacity (95.6%) occurred within 60 h at an initial U(VI) concentration of 20 mg/L. The optimum pH for biosorption was 9.0 at a temperature of 25 °C. X-ray absorption near edge structure analysis confirmed the presence of U(VI) in pellets of Parachlorella sp. AA1 cells. The biosorption methods investigated here may be useful in the treatment and disposal of nuclides and heavy metals in diverse wastewaters.

Rapid Colonization of Uranium Mining-Impacted Waters, the Biodiversity of Successful Lineages of Phytoplankton Extremophiles

Anthropogenic extreme environments are emphasized as interesting sites for the study of evolutionary pathways, biodiversity, and extremophile bioprospection. Organisms that grow under these conditions are usually regarded as extremophiles; however, the extreme novelty of these environments may have favor adaptive radiations of facultative extremophiles. At the Iberian Peninsula, uranium mining operations have rendered highly polluted extreme environments in multiple locations. In this study, we examined the phytoplankton diversity, community structure, and possible determining factors in separate uranium mining-impacted waters. Some of these human-induced extreme environments may be able to sustain indigenous facultative extremophile phytoplankton species, as well as alleged obligate extremophiles. Therefore, we investigated the adaptation capacity of three laboratory strains, two Chlamydomonas reinhardtii and a Dictyosphaerium chlorelloides, to uranium-polluted waters. The biodiversity among the sampled waters was very low, and despite presenting unique taxonomic records, ecological patterns can be identified. The microalgae adaptation experiments indicated a gradient of ecological novelty and different phenomena of adaptation, from acclimation in some waters to non-adaptation in the harshest anthropogenic environment. Certainly, phytoplankton extremophiles might have been often overlooked, and the ability to flourish in extreme environments might be a functional feature in some neutrophilic species. Evolutionary biology and microbial biodiversity can benefit the study of recently evolved systems such as uranium-polluted waters. Moreover, anthropogenic extremophiles can be harnessed for industrial applications.