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Chemosphere Sep 2023Rare earth elements (REE) are valuable raw materials in our modern life. Extensive REE application from electronic devices to medical instruments and wind turbines, and...
Rare earth elements (REE) are valuable raw materials in our modern life. Extensive REE application from electronic devices to medical instruments and wind turbines, and non-uniform distribution of these resources around the world, make them strategically and economically important for countries. Current REE physical and chemical mining and recycling methods could have negative environmental consequences, and biologically-mediated techniques could be applied to overcome this issue. In this study, the bioextraction of cerium oxide and neodymium oxide nanoparticles (REE-NP) by a pure culture Methylobacterium extorquens AM1 (ATCC®14718™) was investigated in batch experiments. Results show that adding up to 1000 ppm CeO or NdO nanoparticles (REE-NP) did not seem to affect the bacterial growth over 14-days contact time. Effect of methylamine hydrochloride as an essential electron donor and carbon source for microbial oxidation and growth was also observed inasmuch as there was approximately no growth when it does not exist in the medium. Although very low concentrations of cerium and neodymium in the liquid phase were measured, concentrations of 45 μg/g Ce and 154 μg/g Nd could be extracted by M. extorquens AM1. Furthermore, SEM-EDS and STEM-EDS confirmed surface and intracellular accumulation of nanoparticles. These results confirmed the ability of M. extorquens to accumulate REE nanoparticles.
Topics: Neodymium; Methylobacterium extorquens; Cerium; Metals, Rare Earth; Nanoparticles
PubMed: 37270036
DOI: 10.1016/j.chemosphere.2023.139113 -
The Science of the Total Environment Aug 2023Many studies have demonstrated that climate change affects the biogeochemical cycle of pollutants, but the mechanisms of arsenic (As) biogeochemical processes under high...
Many studies have demonstrated that climate change affects the biogeochemical cycle of pollutants, but the mechanisms of arsenic (As) biogeochemical processes under high CO levels are unknown. Here, rice pot experiments were carried out to explore the underlying mechanisms of the impacts of elevated CO on the reduction and methylation processes of As in paddy soils. The results revealed that elevated CO might increase As bioavailability and promote As(V)-to-As(III) transformation in the soil as well as higher As(III) and dimethyl arsenate (DMA) accumulation in rice grains, thus increasing health risk. In As-contaminated paddy soil, two key genes involved in the biotransformation of As (arsC and arsM) and associated host microbes were identified as being significantly promoted by increasing CO levels. Elevated CO enriched the soil microbes harboring arsC (Bradyrhizobiaceae and Gallionellaceae), which aided in the reduction of As(V) to As(III). Simultaneously, elevated CO enriched soil microbes harboring arsM (Methylobacteriaceae and Geobacteraceae), allowing As(V) to be reduced to As(III) and then methylated to DMA. The findings of the Incremental Lifetime Cancer Risk (ILTR) assessment suggested that elevated CO exacerbated the individual adult ILTR from rice food As(III) consumption by 9.0 % (p < 0.05). These findings show that elevated CO aggravates the exposure risk of As(III) and DMA in rice grains by changing microbial populations involved in As biotransformation in paddy soils.
Topics: Arsenic; Methylation; Soil; Carbon Dioxide; Oryza; Soil Pollutants
PubMed: 37201836
DOI: 10.1016/j.scitotenv.2023.164240 -
Angewandte Chemie (International Ed. in... Aug 2023Certain f-block elements-the lanthanides-have biological relevance in the context of methylotrophic bacteria. The respective strains incorporate these 4 f elements...
Certain f-block elements-the lanthanides-have biological relevance in the context of methylotrophic bacteria. The respective strains incorporate these 4 f elements into the active site of one of their key metabolic enzymes, a lanthanide-dependent methanol dehydrogenase. In this study, we investigated whether actinides, the radioactive 5 f elements, can replace the essential 4 f elements in lanthanide-dependent bacterial metabolism. Growth studies with Methylacidiphilum fumariolicum SolV and the Methylobacterium extorquens AM1 ΔmxaF mutant demonstrate that americium and curium support growth in the absence of lanthanides. Moreover, strain SolV favors these actinides over late lanthanides when presented with a mixture of equal amounts of lanthanides together with americium and curium. Our combined in vivo and in vitro results establish that methylotrophic bacteria can utilize actinides instead of lanthanides to sustain their one-carbon metabolism if they possess the correct size and a +III oxidation state.
Topics: Lanthanoid Series Elements; Americium; Curium; Methanol; Methylobacterium extorquens; Bacterial Proteins
PubMed: 37074219
DOI: 10.1002/anie.202303669