United States Department of Energy

About: United States Department of Energy is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Coal & Catalysis. The organization has 13656 authors who have published 14177 publications receiving 556962 citations. The organization is also known as: DOE & Department of Energy.

Evidence for bioavailability of Au nanoparticles from soil and biodistribution within earthworms (Eisenia fetida).

Abstract: Because Au nanoparticles (NPs) are resistant to oxidative dissolution and are easily detected, they have been used as stable probes for the behavior of nanomaterials within biological systems. Previous studies provide somewhat limited evidence for bioavailability of Au NPs in food webs, because the spatial distribution within tissues and the speciation of Au was not determined. In this study, we provide multiple lines of evidence, including orthogonal microspectroscopic techniques, as well as evidence from biological responses, that Au NPs are bioavailable from soil to a model detritivore (Eisenia fetida). We also present limited evidence that Au NPs may cause adverse effects on earthworm reproduction. This is perhaps the first study to demonstrate that Au NPs can be taken up by detritivores from soil and distributed among tissues. We found that primary particle size (20 or 55 nm) did not consistently influence accumulated concentrations on a mass concentration basis; however, on a particle number basis the 20 nm particles were more bioavailable. Differences in bioavailability between the treatments may have been explained by aggregation behavior in pore water. The results suggest that nanoparticles present in soil from activities such as biosolids application have the potential to enter terrestrial food webs.

Genome-wide identification of bacterial plant colonization genes.

Abstract: Diverse soil-resident bacteria can contribute to plant growth and health, but the molecular mechanisms enabling them to effectively colonize their plant hosts remain poorly understood We used randomly barcoded transposon mutagenesis sequencing (RB-TnSeq) in Pseudomonas simiae, a model root-colonizing bacterium, to establish a genome-wide map of bacterial genes required for colonization of the Arabidopsis thaliana root system We identified 115 genes (2% of all P simiae genes) with functions that are required for maximal competitive colonization of the root system Among the genes we identified were some with obvious colonization-related roles in motility and carbon metabolism, as well as 44 other genes that had no or vague functional predictions Independent validation assays of individual genes confirmed colonization functions for 20 of 22 (91%) cases tested To further characterize genes identified by our screen, we compared the functional contributions of P simiae genes to growth in 90 distinct in vitro conditions by RB-TnSeq, highlighting specific metabolic functions associated with root colonization genes Our analysis of bacterial genes by sequence-driven saturation mutagenesis revealed a genome-wide map of the genetic determinants of plant root colonization and offers a starting point for targeted improvement of the colonization capabilities of plant-beneficial microbes