The rare-earth elements: Vital to modern technologies and lifestyles

Gosen, Bradley S. Van; Verplanck, Philip L.; Long, Keith R.; Gambogi, Joseph; Seal, Robert R.

doi:10.3133/fs20143078

Cited by 62 publications

(50 citation statements)

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“…In this study, all glassware was acid washed prior to any experiments performed without lanthanides, and all medium components were of the highest purity available. However, lanthanides are a component of some types of glass, and there may have been minute amounts present from this source or from contaminants in the media that allowed some XoxF function and therefore some growth in the ⌬mxa mutants (27). Alternatively, it is possible that another metal present, such as Ca 2ϩ , was able to partially support XoxF activity in the absence of lanthanum.…”

Section: Discussionmentioning

confidence: 99%

“…The decrease of 3 to 4 orders of magnitude in mxa expression by lanthanides in the presence of calcium suggests that XoxF may be the dominant MDH in environmental settings, where lanthanides are relatively abundant (26,27,38). To test this hypothesis in a laboratory setting, an xylE reporter gene was fused to the promoter of mxaF to create an M. buryatense 5GB1C strain with P mxaF -xylE integrated into the chromosome at a region known to be transcriptionally silent (4).…”

Section: Lanthanides Mediate the Mdh Switch In M Buryatense 5gb1cmentioning

confidence: 99%

“…Lanthanides belong to a group of elements known as the rare earth elements, but they are relatively abundant in the Earth's crust despite the group's name (25). Some rare earth elements are present at concentrations similar to those of typical industrial metals (26,27).…”

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confidence: 99%

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XoxF Acts as the Predominant Methanol Dehydrogenase in the Type I Methanotroph Methylomicrobium buryatense

2016

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Many methylotrophic taxa harbor two distinct methanol dehydrogenase (MDH) systems for oxidizing methanol to formaldehyde: the well-studied calcium-dependent MxaFI type and the more recently discovered lanthanide-containing XoxF type. MxaFI has traditionally been accepted as the major functional MDH in bacteria that contain both enzymes. However, in this study, we present evidence that, in a type I methanotroph, Methylomicrobium buryatense, XoxF is likely the primary functional MDH in the environment. The addition of lanthanides increases xoxF expression and greatly reduces mxa expression, even under conditions in which calcium concentrations are almost 100-fold higher than lanthanide concentrations. Mutations in genes encoding the MDH enzymes validate our finding that XoxF is the major functional MDH, as XoxF mutants grow more poorly than MxaFI mutants under unfavorable culturing conditions. In addition, mutant and transcriptional analyses demonstrate that the lanthanide-dependent MDH switch operating in methanotrophs is mediated in part by the orphan response regulator MxaB, whose gene transcription is itself lanthanide responsive. IMPORTANCEAerobic methanotrophs, bacteria that oxidize methane for carbon and energy, require a methanol dehydrogenase enzyme to convert methanol into formaldehyde. The calcium-dependent enzyme MxaFI has been thought to primarily carry out methanol oxidation in methanotrophs. Recently, it was discovered that XoxF, a lanthanide-containing enzyme present in most methanotrophs, can also oxidize methanol. In a methanotroph with both MxaFI and XoxF, we demonstrate that lanthanides transcriptionally control genes encoding the two methanol dehydrogenases, in part by controlling expression of the response regulator MxaB. Lanthanides are abundant in the Earth's crust, and we demonstrate that micromolar amounts of lanthanides are sufficient to suppress MxaFI expression. Thus, we present evidence that XoxF acts as the predominant methanol dehydrogenase in a methanotroph.A n increasing surplus in the global methane budget exists due to human activity. The industrial use of microorganisms to convert methane into useful chemicals or biofuels represents one way to mitigate atmospheric methane (1, 2). Methanotrophs, or methane-oxidizing bacteria, utilize methane as their carbon and energy source and are prime candidates for the industrial bioconversion of methane (1). Renewed interest in the industrial use of methanotrophs has come about partially because of the discovery of rapidly growing strains and new tools for genetic manipulation, allowing for fast-paced metabolic engineering (3, 4). The success of metabolic engineering strategies in these methanotrophs depends upon a strong foundation of knowledge concerning the metabolic pathways that methanotrophs employ, both in the laboratory and in their natural environments, and an understanding of how various branches of metabolic pathways are regulated.The majority of methanotrophs have two systems for oxidizing methane to methanol: the parti...

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Section: Discussionmentioning

confidence: 99%

Section: Lanthanides Mediate the Mdh Switch In M Buryatense 5gb1cmentioning

confidence: 99%

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XoxF Acts as the Predominant Methanol Dehydrogenase in the Type I Methanotroph Methylomicrobium buryatense

2016

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“…Erosion or weathering of primary types may produce deposits, such as placer and ion adsorption deposits [20]. In this paper, based on the USGS classification [21,28,29], we split rare earth deposit types into carbonatite, alkaline igneous rock, placer, ion adsorption, iron-oxide copper-gold (IOCG) deposits, and others. In general, rare earth deposits associated with alkaline igneous rocks are of rather low grade, but may exist in large tonnage and relatively enriched in the HREE, such as Lovozero in Russia (containing 6.6 megaton (Mt) REO at 1.12%) [30].…”

Section: Identification Of Global Rare Earth Resourcesmentioning

confidence: 99%

Global Potential of Rare Earth Resources and Rare Earth Demand from Clean Technologies

2017

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Rare earth elements (REE) are widely used in high technologies, medical devices, and military defense systems, and are especially indispensable in emerging clean energy. Along with the growing market of green energy in the next decades, global demand for REE will increase continuously, which will put great pressure on the current REE supply chain. The global REE production is currently mainly concentrated in China and Australia; they respectively contributed 85% and 10% in 2016. However, there are 178 deposits widely distributed in the world, and reported REE resources as of 2017 totaled 478 megaton (Mt) rare earth oxides (REO); 58% of these deposits contained exceed 0.1 Mt REO; 59 deposits have been technically assessed. These resources could sustain the global REE production at the current pace for more than a hundred years. It is noted that REE demand from clean technologies will reach 51.9 thousand metric tons (kt) REO in 2030, Nd and Dy, respectively, comprising 75% and 9%, while these two elements comprise 15% and 0.52% of the global REE resources, respectively. This indicates that Nd and Dy will strongly influence the development of exploring new REE projects and clean technologies in the next decades.

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“…Clean energy technologies, such as electric vehicles and wind turbines, have increased demand for permanent magnets, and particularly Nd-Fe-B rare earth magnets that are used in electric motors and generators (Alonso et al 2012;Smith Stegen 2015;U.S. Department of Energy 2010;Van Gosen et al 2014;Zhou et al 2017). Nd-Fe-B permanent magnets have become the dominant magnet chemistry because of their significantly stronger magnetic fields than other types of magnets.…”

Section: Introductionmentioning

confidence: 99%

Life cycle assessment with primary data on heavy rare earth oxides from ion-adsorption clays

Deng

Kendall

2019

Int J Life Cycle Assess

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Heavy and light rare earth elements (REEs) are critical to clean energy technologies, and thus the environmental impacts from their production are increasingly scrutinized. Most previous LCAs of REE production focus on sites producing light REEs. This research addresses this gap by collecting primary data from sites producing heavy rare earth oxides (HREOs) from ion-adsorption clays, conducting an LCA, and providing open-source life cycle inventory (LCI) datasets of HREO production for the LCA community. Methods This study conducts a LCA based on acquired primary data from four mining sites in Jiangxi Province, China. The functional unit is 1 kg of mixed HREOs of 90% purity from ion-adsorption clays using the technology of in situ leaching. Previous studies have used the Ecoinvent database, relying mostly European or global life cycle inventories (LCIs). Here, the Chinese Life Cycle Database provided China-specific reference life cycle inventories (LCIs). The Ecoinvent 3 database was also used in this study, however, for electricity generation LCIs used in a scenario analysis evaluating China's changing grid mix (Wernet et al. 2016). Twelve impact categories were examined using Impact 2 2002+, USEtox 2.01 and IPCC methods. Results are provided as a bounded range, reflecting low and high estimates based on collected primary data. Results and discussion Results show 1 kg of mixed HREOs emit 258-408 kg CO2e, and consume 270-443 MJ primary energy. These values fall within the range of previous LCAs that examined both bastnaesite/monazite deposits and ion-adsorption clays using literature values. Other impact categories considered are not similar across studies, however. Differences are due to variability in resource type and quality, technology, and modeling choices, such as reference LCI sources. Mining and extraction contribute most to impacts due to large quantities of chemicals for leaching and precipitation of REOs, and electricity consumption. Among chemicals, ammonium sulfate is the largest contributor to many impact categories. When China's electricity grid mix change over time is included, environmental impacts for the whole production process can change up to 12%. Conclusions The primary contributions of this study are the collection and publication of primary data from mining companies in Jiangxi Province, China; the provision of open-source LCI datasets for mixed HREOs from ion-adsorption clays; and a comparison of results between this study and previously published studies. While the scope of this study concludes at the production of mixed HREO, which is a limitation, it provides a foundation for development of LCIs for refined heavy REEs.

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The rare-earth elements: Vital to modern technologies and lifestyles

Cited by 62 publications

References 0 publications

XoxF Acts as the Predominant Methanol Dehydrogenase in the Type I Methanotroph Methylomicrobium buryatense

XoxF Acts as the Predominant Methanol Dehydrogenase in the Type I Methanotroph Methylomicrobium buryatense

Global Potential of Rare Earth Resources and Rare Earth Demand from Clean Technologies

Life cycle assessment with primary data on heavy rare earth oxides from ion-adsorption clays

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