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- All Subjects: Biochemistry
Description
In our modern world the source of for many chemicals is to acquire and refine oil. This process is becoming an expensive to the environment and to human health. Alternative processes for acquiring the final product have been developed but still need work. One product that is valuable is butanol. The normal process for butanol production is very intensive but there is a method to produce butanol from bacteria. This process is better because it is more environmentally safe than using oil. One problem however is that when the bacteria produce too much butanol it reaches the toxicity limit and stops the production of butanol. In order to keep butanol from reaching the toxicity limit an adsorbent is used to remove the butanol without harming the bacteria. The adsorbent is a mesoporous carbon powder that allows the butanol to be adsorbed on it. This thesis explores different designs for a magnetic separation process to extract the carbon powder from the culture.
ContributorsChabra, Rohin (Author) / Nielsen, David (Thesis director) / Torres, Cesar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
Styrene, a component of many rubber products, is currently synthesized from petroleum in a highly energy-intensive process. The Nielsen Laboratory at Arizona State has demonstrated a biochemical pathway by which E. coli can be engineered to produce styrene from the amino acid phenylalanine, which E. coli naturally synthesizes from glucose. However, styrene becomes toxic to E. coli above concentrations of 300 mg/L, severely limiting the large-scale applicability of the pathway. Thus, styrene must somehow be continuously removed from the system to facilitate higher yields and for the purposes of scale-up. The separation methods of pervaporation and solvent extraction were investigated to this end. Furthermore, the styrene pathway was extended by one step to produce styrene oxide, which is less volatile than styrene and theoretically simpler to recover. Adsorption of styrene oxide using the hydrophobic resin L-493 was attempted in order to improve the yield of styrene oxide and to provide additional proof of concept that the flux through the styrene pathway can be increased. The maximum styrene titer achieved was 1.2 g/L using the method of solvent extraction, but this yield was only possible when additional phenylalanine was supplemented to the system.
ContributorsMcDaniel, Matthew Cary (Author) / Nielsen, David (Thesis director) / Lind, Mary Laura (Committee member) / McKenna, Rebekah (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / Chemical Engineering Program (Contributor)
Created2013-05
Description
The world today needs novel solutions to address current challenges in areas spanning areas from sustainable manufacturing to healthcare, and biotechnology offers the potential to help address some of these issues. One tool that offers opportunities across multiple industries is the use of nonribosomal peptide synthases (NRPSs). These are modular biological factories with individualized subunits that function in concert to create novel peptides.One element at the heart of environmental health debates today is plastics. Biodegradable alternatives for petroleum-based plastics is a necessity. One NRPS, cyanophycin synthetase (CphA), can produce cyanophycin grana protein (CGP), a polymer composed of a poly-aspartic acid backbone with arginine side chains. The aspartic backbone has the potential to replace synthetic polyacrylate, although current production costs are prohibitive. In Chapter 2, a CphA variant from Tatumella morbirosei is characterized, that produces up to 3x more CGP than other known variants, and shows high iCGP specificity in both flask and bioreactor trials. Another CphA variant, this one from Acinetobacter baylyi, underwent rational protein design to create novel mutants. One, G217K, is 34% more productive than the wild type, while G163K produces a CGP with shorter chain lengths. The current structure refined from 4.4Å to 3.5Å.
Another exciting application of NRPSs is in healthcare. They can be used to generate novel peptides such as complex antibiotics. A recently discovered iterative polyketide synthase (IPTK), dubbed AlnB, produces an antibiotic called allenomycin. One of the modular subunits, a dehydratase named AlnB_DH, was crystallized to 2.45Å. Several mutations were created in multiple active site residues to help understand the functional mechanism of AlnB_DH. A preliminary holoenzyme AlnB structure at 3.8Å was generated although the large disorganized regions demonstrated an incomplete structure. It was found that chain length is the primary factor in driving dehydratase action within AlnB_DH, which helps lend understanding to this module.
ContributorsSwain, Kyle (Author) / Nannenga, Brent (Thesis advisor) / Nielsen, David (Committee member) / Mills, Jeremy (Committee member) / Seo, Eileen (Committee member) / Acharya, Abhinav (Committee member) / Arizona State University (Publisher)
Created2022