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ABSTRACT Communication is vital in the context of everyday life for all organisms, but particularly so in social insects, such as Z. nevadensis. The overall lifestyle and need for altruistic acts of individuals within a colony depends primarily on intracolony chemical communication, with a focus on odorants. The perception of

ABSTRACT Communication is vital in the context of everyday life for all organisms, but particularly so in social insects, such as Z. nevadensis. The overall lifestyle and need for altruistic acts of individuals within a colony depends primarily on intracolony chemical communication, with a focus on odorants. The perception of these odorants is made possible by the chemoreceptive functions of sensilla basiconica and sensilla trichoid which exist on the antennal structure. The present study consists of both a morphological analysis and electrophysiological experiment concerning sensilla basiconica. It attempts to characterize the function of neurons present in sensilla basiconica through single sensillum recordings and contributes to existing literature by determining if a social insect, such as the dampwood termite, is able to perceive a wide spectrum of odorants despite having significantly fewer olfactory receptors than most other social insect species. Results indicated that sensilla basiconica presence significantly out-paced that of sensilla trichoid and sensilla chaetica combined, on all flagellomeres. Analysis demonstrated significant responses to all general odorants and several cuticular hydrocarbons. Combined with the knowledge of fewer olfactory receptors present in this species and their lifestyle, results may indicate a positive association between the the social complexity of an insect's lifestyle and the number of ORs the individuals within that colony possess.
ContributorsMcGlone, Taylor (Author) / Liebig, Juergen (Thesis director) / Ghaninia, Majid (Committee member) / Barrett, The Honors College (Contributor)
Created2015-05
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This project was completed to understand the evolution of the ability to digest wood in termite symbiotic protists. Lower termites harbor bacterial and protist symbionts which are essential to the termite ability to use wood as a nutritional source, producing glycoside hydrolases to break down the polysaccharides found in lignocellulose.

This project was completed to understand the evolution of the ability to digest wood in termite symbiotic protists. Lower termites harbor bacterial and protist symbionts which are essential to the termite ability to use wood as a nutritional source, producing glycoside hydrolases to break down the polysaccharides found in lignocellulose. Yet, only a few molecular studies have been done to confirm the protist species responsible for particular enzymes. By mining publicly available and newly generated genomic and transcriptomic data, including three transcriptomes from isolated protist cells, I identify over 200 new glycoside hydrolase sequences and compute the phylogenies of eight glycoside hydrolase families (GHFs) reported to be expressed by termite hindgut protists.

Of those families examined, the results are broadly consistent with Todaka et al. 2010, though none of the GHFs found were expressed in both termite-associated protist and non-termite-associated protist transcriptome data. This suggests that, rather than being inherited from their free-living protist ancestors, GHF genes were acquired by termite protists while within the termite gut, potentially via lateral gene transfer (LGT). For example one family, GHF10, implies a single acquisition of a bacterial xylanase into termite protists. The phylogenies from GHF5 and GHF11 each imply two distinct acquisitions in termite protist ancestors, each from bacteria. In eukaryote-dominated GHFs, GHF7 and GHF45, there are three apparent acquisitions by termite protists. Meanwhile, it appears prior reports of GHF62 in the termite gut may have been misidentified GHF43 sequences. GHF43 was the only GHF found to contain sequences from the protists not found in the termite gut. These findings generally all support the possibility termite-associated protists adapted to a lignocellulosic diet after colonization of the termite hindgut. Nonetheless, the poor resolution of GHF phylogeny and limited termite and protist sampling constrain interpretation.
ContributorsSanderlin, Viola (Author) / Gile, Gillian H (Thesis advisor) / Wojciechowski, Martin (Committee member) / Weiss, Taylor (Committee member) / Varman, Arul Mozhy (Committee member) / Arizona State University (Publisher)
Created2019
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Esters are important solvents in multiple industries including adhesives, food, and pharmaceuticals. Although esters are biodegradable solvents, the conventional process of producing them is not eco-friendly because they are largely derived from petrochemicals. This has led scientists to consider implementing biological routes in their production process by incorporating heterologous or

Esters are important solvents in multiple industries including adhesives, food, and pharmaceuticals. Although esters are biodegradable solvents, the conventional process of producing them is not eco-friendly because they are largely derived from petrochemicals. This has led scientists to consider implementing biological routes in their production process by incorporating heterologous or improving inherent esterification pathways. However, due to inequality in the biosynthesis of esters and their precursors (organic acid and alcohol), a significant amount of precursors are left unconverted, thereby lowering overall esterification efficiency. Therefore, the primary goal of the current research is to improve the ester titers by incorporating one more step of in vitro esterification with the culture broth, thereby esterifying the unconverted precursors using high efficiency commercial enzymes in the presence of compatible organic solvent. In principle, the medium containing the precursors will be treated with the enzyme in presence of organic solvent, where the precursors will be distributed in both the phases, aqueous and organic, based on their polarity, and the enzymatic esterification will happen at the interface. Hence, as a first step, efforts were made to optimize the reaction conditions, beginning with choosing the most efficient organic solvent and corresponding enzyme candidate. Our results showed that, for production of ethyl acetate through this reactive extraction approach, Novozyme435 exhibited significant esterification with chloroform, with almost 85% conversion efficiency. Further optimizations with phase ratios, pH and incubation time showed that the pH 6.0 (3.1 g/L) was the most optimum where ethyl acetate titer was found to improve 10 times than that at pH 7.0 (0.164 g/L) with the phase ratio of 1:1. The kinetic studies further added that the incubation at 37oC gives the maximum ethyl acetate production within 8h. After initial optimization studies, cell broth from E. coli cells transformed to overproduce an esterase was also tested with the reactive extraction method. It was found that there was a ~7.5X decrease in ethyl acetate production in the cell media versus synthetic samples with the same concentration of reactants. Such a large decrease indicates that enzymatic promiscuity or inhibition currently prevent the cell samples from reaching the same conversion as synthetic studies. To characterize the maximum reaction rate (Vmax) and affinity constants of the substrates to Novozym 435, further kinetic studies were performed with one minute of reaction. The mathematical model employed assumes that enzyme kinetics rather than diffusion was the rate limiting step, that the concentrations of reactants at the interface are equivalent to the initial concentration of reactants, and that neither substrate is an inhibitor. Vmax was found to be 18.5 Mmol min-1g-1 (of catalyst used), and the affinity constants were 0.957 M and 0.00557 M for acetic acid and ethanol respectively. Vmax was similar to literature values with Novozym 435, and the affinity constants indicate a much higher binding efficiency of ethanol in comparison to acetic acid, indicating that a cocktail of esters are likely produced from Novozym 435 in cell broth. Overall, moving away from fossil-fuel dependence is necessary to promote sustainable industry standards, and microbial cell factories combined with reactive extraction, if optimized for industrial applications, can replace harmful environmental procedures. By optimizing the reactive extraction process for ester production, biorefineries could become more competitive and economically feasible for numerous applications.

ContributorsKartchner, Danika (Author) / Varman, Arul Mozhy (Thesis director) / Nielsen, David (Committee member) / Soundappan, Thiagarajan (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / Watts College of Public Service & Community Solut (Contributor)
Created2022-05