Browsing by Subject "Biotechnology Institute"

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    Analysis of a Genetic Adaptation for Glycerol Utilization: Implications for Microbial Fuel Cells
    (2010-04-21) Torchia, Mike
    Biodiesel promises a renewable source of energy yet is unable to be an economically viable alternative to petroleum. One way to solve this is to convert glycerol, a by-product of the biodiesel production process, to higher value commodities. Shewanella oneidensis can respire insoluble extracellular substrates such as electrodes. Furthermore, when the pGUT2PET plasmid is transformed into wild type S. oneidensis, the non-redox balanced conversion of glycerol to ethanol is permitted. This engineered bacterium permits the generation of two higher value products (ethanol and electricity) from the original glycerol feedstock. Since any future industrial application of this microbe will necessitate optimization of all its parameters, we were interested in studying how S. oneidensis grows faster on glycerol.
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    Expression and purification of GxcA, a c-type cytochrome involved with metal respiration by the bacterium, Geothrix fermentans
    (2011-04-13) Liu, Joanne
    The study of bacteria capable of respiring oxidized metals offers insights into the geochemical cycling of metals, including toxic heavy metal contaminants. These dissimilatory metal-reducing organisms couple oxidation of organic compounds with the reduction of substrates to gain energy. Improving understanding of the various bacterial metal-reducing strategies will increase our ability to produce renewable energy using microbial fuel cell technologies. The bacterium Geothrix fermentanshas long been ignored in the study of metal respiration, but it has recently been shown to employ a unique strategy involving more than one biochemical pathway that appears tuned to use of high potential metals, such as uranium and manganese. Membranes isolated from Fe(III)-respiring G. fermentans contain high levels of a decahemecytochrome, known as GxcA, which is suspected in electron transfer by G. fermentans. As a genetic system for G. fermentans is not yet available, GxcAwas targeted for expression and purification. The DNA sequence for GxcA, containing an in-frame hexahistidinesequence, was first cloned into E. coli, using the inducible expression vector pETlite. Then, the recombinant plasmid was co-transformed into E. coli with pEC86, a plasmid that contains genes for the ccmc-type cytochrome maturation system. Colonies were screened for c-type cytochromes by redox difference absorption analysis and hemestain analysis. Future work will involve GxcApurification for redox and localization experiments to determine GxcA’spotential role in G. fermentans.