Patrick Clark Hallenbeck

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The molecular details behind hydrogen evolution during fermentation are reviewed. Hydrogen is evolved by hydrogenase, a class of enzymes containing complex metallo-centers. In most cases, sugars are degraded to pyruvate which in turn is converted to a variety of fermentation products. Various pathways leading to fermentative hydrogen generation are outlined(More)
The soluble form of a bacteriophage-induced endo-N-acetylneuraminidase (Endo-N) specific for hydrolyzing oligo- or poly-alpha-2,8-linked sialosyl units in sources as disparate as bacterial and neural membrane glycoconjugates was purified approximately 10,000-fold and characterized. The enzyme appears homogenous by sodium dodecyl sulfate-polyacrylamide gel(More)
As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga(More)
In most bacteria, nitrogen metabolism is tightly regulated and P(II) proteins play a pivotal role in the regulatory processes. Rhodobacter capsulatus possesses two genes (glnB and glnK) encoding P(II)-like proteins. The glnB gene forms part of a glnB-glnA operon and the glnK gene is located immediately upstream of amtB, encoding a (methyl-) ammonium(More)
A significant effort is underway to develop biofuels as replacements for non-renewable fossil fuels. Among the various options, hydrogen is an attractive future energy carrier due to its potentially higher efficiency of conversion to usable power, low generation of pollutants and high energy density. There are a variety of technologies for biological(More)
Beet molasses and black strap are two major waste streams of the sugar industry. They both contain high amounts of sucrose, making them suitable substrates for biological hydrogen production. Photofermentation, usually used to convert organic acids to hydrogen, has the potential capacity to effectively use a variety of feed stocks, including sugars. A(More)
Dramatically rising oil prices and increasing awareness of the dire environmental consequences of fossil fuel use, including startling effects of climate change, are refocusing attention worldwide on the search for alternative fuels. Hydrogen is poised to become an important future energy carrier. Renewable hydrogen production is pivotal in making it a(More)
Biodiesel produced from microalgal lipids is being considered as a potential source of renewable energy. However, a number of hurdles will have to be overcome if such a process is to become practical. One important factor is the volumetric production of biomass and lipid that can be achieved. The marine alga Nannochloropsis gaditana is under study since it(More)
Biodiesel production from microalgae lipids is being considered as a potential source of renewable energy. However, practical production processes will probably require the use of local strains adapted to prevailing climatic conditions. This report describes the isolation of 100 microalgal strains from freshwater lakes and rivers located in the vicinity of(More)
Rhodobacter capsulatus possesses two genes potentially coding for ammonia transporters, amtB and amtY. In order to better understand their role in the physiology of this bacterium and their possible significance in nitrogen fixation, we created single-knockout mutants. Strains mutated in either amtB or amtY did not show a growth defect under any condition(More)