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.

Comparative genomics of xylose-fermenting fungi for enhanced biofuel production

Abstract: Cellulosic biomass is an abundant and underused substrate for biofuel production. The inability of many microbes to metabolize the pentose sugars abundant within hemicellulose creates specific challenges for microbial biofuel production from cellulosic material. Although engineered strains of Saccharomyces cerevisiae can use the pentose xylose, the fermentative capacity pales in comparison with glucose, limiting the economic feasibility of industrial fermentations. To better understand xylose utilization for subsequent microbial engineering, we sequenced the genomes of two xylose-fermenting, beetle-associated fungi, Spathaspora passalidarum and Candida tenuis. To identify genes involved in xylose metabolism, we applied a comparative genomic approach across 14 Ascomycete genomes, mapping phenotypes and genotypes onto the fungal phylogeny, and measured genomic expression across five Hemiascomycete species with different xylose-consumption phenotypes. This approach implicated many genes and processes involved in xylose assimilation. Several of these genes significantly improved xylose utilization when engineered into S. cerevisiae, demonstrating the power of comparative methods in rapidly identifying genes for biomass conversion while reflecting on fungal ecology.

Understanding the sensor response of metal-decorated carbon nanotubes.

Abstract: We have explored the room temperature response of metal nanoparticle decorated single-walled carbon nanotubes (NP-SWNTs) using a combination of electrical transport, optical spectroscopy, and electronic structure calculations. We have found that upon the electrochemical growth of Au NPs on SWNTs, there is a transfer of electron density from the SWNT to the NP species, and that adsorption of CO molecules on the NP surface is accompanied by transfer of electronic density back into the SWNT. Moreover, the electronic structure calculations indicate dramatic variations in the charge density at the NP-SWNT interface, which supports our previous observation that interfacial potential barriers dominate the electrical behavior of NP-SWNT systems.

Systematic modulation and enhancement of CO2 : N2 selectivity and water stability in an isoreticular series of bio-MOF-11 analogues

Abstract: An isoreticular series of cobalt-adeninate bio-MOFs (bio-MOFs-11–14) is reported. The pores of bio-MOFs-11–14 are decorated with acetate, propionate, butyrate, and valerate, respectively. The nitrogen (N2) and carbon dioxide (CO2) adsorption properties of these materials are studied and compared. The isosteric heats of adsorption for CO2 are calculated, and the CO2 : N2 selectivities for each material are determined. As the lengths of the aliphatic chains decorating the pores in bio-MOFs-11–14 increase, the BET surface areas decrease from 1148 m2 g−1 to 17 m2 g−1 while the CO2 : N2 selectivities predicted from ideal adsorbed solution theory at 1 bar and 273 K for a 10 : 90 CO2 : N2 mixture range from 73 : 1 for bio-MOF-11 to 123 : 1 for bio-MOF-12 and finally to 107 : 1 for bio-MOF-13. At 298 K, the selectivities are 43 : 1 for bio-MOF-11, 52 : 1 for bio-MOF-12, and 40 : 1 for bio-MOF-13. Additionally, it is shown that bio-MOF-14 exhibits a unique molecular sieving property that allows it to adsorb CO2 but not N2 at 273 and 298 K. Finally, the water stability of bio-MOFs-11–14 increases with increasing aliphatic chain length. Bio-MOF-14 exhibits no loss of crystallinity or porosity after soaking in water for one month.