@misc{noar_bruno-barcena_2016, title={Protons and pleomorphs: aerobic hydrogen production in Azotobacters}, volume={32}, ISSN={["1573-0972"]}, url={http://europepmc.org/abstract/med/26748806}, DOI={10.1007/s11274-015-1980-5}, abstractNote={As obligate aerobic soil organisms, the ability of Azotobacter species to fix nitrogen is unusual given that the nitrogenase complex requires a reduced cellular environment. Molecular hydrogen is an unavoidable byproduct of the reduction of dinitrogen; at least one molecule of H2 is produced for each molecule of N2 fixed. This could be considered a fault in nitrogenase efficiency, essentially a waste of energy and reducing equivalents. Wild-type Azotobacter captures this hydrogen and oxidizes it with its membrane-bound uptake hydrogenase complex. Strains lacking an active hydrogenase complex have been investigated for their hydrogen production capacities. What is the role of H2 in the energy metabolism of nitrogen-fixing Azotobacter? Is hydrogen production involved in Azotobacter species' protection from or tolerance to oxygen, or vice versa? What yields of hydrogen can be expected from hydrogen-evolving strains? Can the yield of hydrogen be controlled or increased by changing genetic, environmental, or physiological conditions? We will address these questions in the following mini-review.}, number={2}, journal={WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY}, author={Noar, Jesse D. and Bruno-Barcena, Jose M.}, year={2016}, month={Feb} } @article{noar_loveless_luis navarro-herrero_olson_bruno-barcena_2015, title={Aerobic Hydrogen Production via Nitrogenase in Azotobacter vinelandii CA6}, volume={81}, ISSN={["1098-5336"]}, url={http://europepmc.org/abstract/med/25911479}, DOI={10.1128/aem.00679-15}, abstractNote={ABSTRACT The diazotroph Azotobacter vinelandii possesses three distinct nitrogenase isoenzymes, all of which produce molecular hydrogen as a by-product. In batch cultures, A. vinelandii strain CA6, a mutant of strain CA, displays multiple phenotypes distinct from its parent: tolerance to tungstate, impaired growth and molybdate transport, and increased hydrogen evolution. Determining and comparing the genomic sequences of strains CA and CA6 revealed a large deletion in CA6's genome, encompassing genes related to molybdate and iron transport and hydrogen reoxidation. A series of iron uptake analyses and chemostat culture experiments confirmed iron transport impairment and showed that the addition of fixed nitrogen (ammonia) resulted in cessation of hydrogen production. Additional chemostat experiments compared the hydrogen-producing parameters of different strains: in iron-sufficient, tungstate-free conditions, strain CA6's yields were identical to those of a strain lacking only a single hydrogenase gene. However, in the presence of tungstate, CA6 produced several times more hydrogen. A. vinelandii may hold promise for developing a novel strategy for production of hydrogen as an energy compound. }, number={13}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Noar, Jesse and Loveless, Telisa and Luis Navarro-Herrero, Jose and Olson, Jonathan W. and Bruno-Barcena, Jose M.}, year={2015}, month={Jul}, pages={4507–4516} } @article{nawalakhe_shi_vitchuli_noar_caldwell_breidt_bourham_zhang_mccord_2013, title={Novel atmospheric plasma enhanced chitosan nanofiber/gauze composite wound dressings}, volume={129}, ISSN={0021-8995}, url={http://dx.doi.org/10.1002/app.38804}, DOI={10.1002/app.38804}, abstractNote={AbstractElectrospun chitosan nanofibers were deposited onto atmospheric plasma treated cotton gauze to create a novel composite bandage with higher adhesion, better handling properties, enhanced bioactivity, and moisture management. Plasma treatment of the gauze substrate was performed to improve the durability of the nanofiber/gauze interface. The chitosan nanofibers were electrospun at 3–7% concentration in trifluoroacetic acid. The composite bandages were analyzed using peel, gelbo flex, antimicrobial assay, moisture vapor transmission rate, X‐ray photoelectron spectroscopy (XPS), absorbency, and air permeability tests. The peel test showed that plasma treatment of the substrate increased the adhesion between nanofiber layers and gauze substrate by up to four times. Atmospheric plasma pretreatment of the gauze fabric prior to electrospinning significantly reduced degradation of the nanofiber layer due to repetitive flexing. The chitosan nanofiber layer contributes significantly to the antimicrobial properties of the bandage. Air permeability and moisture vapor transport were reduced due to the presence of a nanofiber layer upon the substrate. XPS of the plasma treated cotton substrate showed formation of active sites on the surface, decrease in carbon content, and increase in oxygen content as compared to the untreated gauze. Deposition of chitosan nanofibers also increased the absorbency of gauze substrate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013}, number={2}, journal={Journal of Applied Polymer Science}, publisher={Wiley}, author={Nawalakhe, Rupesh and Shi, Quan and Vitchuli, Narendiran and Noar, Jesse and Caldwell, Jane M. and Breidt, Frederick and Bourham, Mohamed A. and Zhang, Xiangwu and McCord, Marian G.}, year={2013}, month={Feb}, pages={916–923} }