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- Creators: School of International Letters and Cultures
- Creators: Torres, Cesar
Description
Metabolic engineering is an extremely useful tool enabling the biosynthetic production of commodity chemicals (typically derived from petroleum) from renewable resources. In this work, a pathway for the biosynthesis of styrene (a plastics monomer) has been engineered in Escherichia coli from glucose by utilizing the pathway for the naturally occurring amino acid phenylalanine, the precursor to styrene. Styrene production was accomplished using an E. coli phenylalanine overproducer, E. coli NST74, and over-expression of PAL2 from Arabidopsis thaliana and FDC1 from Saccharomyces cerevisiae. The styrene pathway was then extended by just one enzyme to either (S)-styrene oxide (StyAB from Pseudomonas putida S12) or (R)-1,2-phenylethanediol (NahAaAbAcAd from Pseudomonas sp. NCIB 9816-4) which are both used in pharmaceutical production. Overall, these pathways suffered from limitations due to product toxicity as well as limited precursor availability. In an effort to overcome the toxicity threshold, the styrene pathway was transferred to a yeast host with a higher toxicity limit. First, Saccharomyces cerevisiae BY4741 was engineered to overproduce phenylalanine. Next, PAL2 (the only enzyme needed to complete the styrene pathway) was then expressed in the BY4741 phenylalanine overproducer. Further strain improvements included the deletion of the phenylpyruvate decarboxylase (ARO10) and expression of a feedback-resistant choristmate mutase (ARO4K229L). These works have successfully demonstrated the possibility of utilizing microorganisms as cellular factories for the production styrene, (S)-styrene oxide, and (R)-1,2-phenylethanediol.
ContributorsMcKenna, Rebekah (Author) / Nielsen, David R (Thesis advisor) / Torres, Cesar (Committee member) / Caplan, Michael (Committee member) / Jarboe, Laura (Committee member) / Haynes, Karmella (Committee member) / Arizona State University (Publisher)
Created2014
Description
Adenosine triphosphate (ATP) is the driving force of the human body which allows individuals to move freely. Metabolism is responsible for its creation, and research has indicated that with training, metabolism can be modified to respond more efficiently to aerobic stimulus. During an acute bout of exercise, cardiac output increases to maintain oxygen supply to the body. Oxidative muscle fibers contract to move the body for prolonged periods of time, creating oxidative stress which is managed by the mitochondria which produce the ATP that supplies the muscle fiber, and as the body returns to its resting state, oxygen continues to be consumed in order to return to steady state. Following endurance training, changes in cardiac output, muscle fiber types, mitochondria, substrate utilization, and oxygen consumption following exercise make adaptations to make metabolism more efficient. Resting heart rate decreases and stroke volume increases. Fast twitch muscle fibers shift into more oxidative fibers, sometimes through mitochondrial biogenesis, and more fat is able to be utilized during exercise. The excess postexercise oxygen consumption following exercise bouts is reduced, and return to steady state becomes quicker. In conclusion, endurance training optimizes metabolic response during acute bouts of aerobic exercise.
ContributorsWarner, Erin (Author) / Nolan, Nicole (Thesis director) / Cataldo, Donna (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Early humans adapted to eating cooked food with increased energy density and absorption of macronutrients. However, in modern times many suffer from diseases like obesity and type 2 diabetes which can result from too much energy being absorbed from food. This study measures glucose responses to a high glycemic meal with a side dish of raw or cooked vegetables. There was a slight trend for raw vegetables to have decreased postprandial blood glucose responses when compared to cooked vegetables.
ContributorsWilkins, Christine Marie (Author) / Johnston, Carol (Thesis director) / Jacobs, Mark (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor)
Created2014-05
Description
This dissertation focuses on the biosynthetic production of aromatic fine chemicals in engineered Escherichia coli from renewable resources. The discussed metabolic pathways take advantage of key metabolites in the shikimic acid pathway, which is responsible for the production of the aromatic amino acids phenylalanine, tyrosine, and tryptophan. For the first time, the renewable production of benzaldehyde and benzyl alcohol has been achieved in recombinant E. coli with a maximum titer of 114 mg/L of benzyl alcohol. Further strain development to knockout endogenous alcohol dehydrogenase has reduced the in vivo degradation of benzaldehyde by 9-fold, representing an improved host for the future production of benzaldehyde as a sole product. In addition, a novel alternative pathway for the production of protocatechuate (PCA) and catechol from the endogenous metabolite chorismate is demonstrated. Titers for PCA and catechol were achieved at 454 mg/L and 630 mg/L, respectively. To explore potential routes for improved aromatic product yields, an in silico model using elementary mode analysis was developed. From the model, stoichiometric optimums maximizing both product-to-substrate and biomass-to-substrate yields were discovered in a co-fed model using glycerol and D-xylose as the carbon substrates for the biosynthetic production of catechol. Overall, the work presented in this dissertation highlights contributions to the field of metabolic engineering through novel pathway design for the biosynthesis of industrially relevant aromatic fine chemicals and the use of in silico modelling to identify novel approaches to increasing aromatic product yields.
ContributorsPugh, Shawn (Author) / Nielsen, David (Thesis advisor) / Dai, Lenore (Committee member) / Torres, Cesar (Committee member) / Lind, Mary Laura (Committee member) / Wang, Xuan (Committee member) / Arizona State University (Publisher)
Created2016
ContributorsRizvi, Hasan (Author) / Hyatt, JP (Thesis director) / Kingsbury, Jeffrey (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Molecular Sciences (Contributor)
Created2023-05
Description
Our current understanding of the mitochondrial genome was revolutionized in 2015 with the discovery of short open reading frames (sORFs) that produced protein products called mitochondrial-derived peptides (MDPs). Interestingly, unlike other proteins produced by the organelle, these MDPs are not directly involved in the electron transport chain but rather serve the role of metabolic regulators. In particular, one of these peptides called MOTS-c has been shown to regulate glucose and fat metabolism in an AMPK-dependent manner. With its capacity to enter the mitochondria and impact gene expression, MOTS-c has also displayed the ability to increase aerobic exercise performance by triggering elevated synthesis of the HO-1 antioxidant. Overall these findings position MOTS-c as a promising treatment for metabolic diseases as well as a potential dietary supplement to boost ATP availability.
ContributorsRizvi, Hasan (Author) / Hyatt, JP (Thesis director) / Kingsbury, Jeffrey (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Molecular Sciences (Contributor)
Created2023-05
ContributorsRizvi, Hasan (Author) / Hyatt, JP (Thesis director) / Kingsbury, Jeffrey (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Molecular Sciences (Contributor)
Created2023-05