Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Thesis documentation sheet inserted. Appendix reprints three papers and manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix.

Thesis (Ph.D.)--Baylor University, 2006. / In abstracts "- and 2" are superscript. In abstracts "3 and 2" are subscript. Includes bibliographical references (p. 105-114).

This thesis concerns the mechanism of oxidative phosphorylation, with special reference to the bacterium Paracoccus denitrificans. A new method using affinity chromatography is described for the separation of vesicles of different membrane orientation. The working hypothesis is the chemisosmotic theory of Mitchell with its emphasis on the transmembrane proton motive force made up of a membrane potential and a transmembrane pH gradient. The 3 experimental systems used ape bovine heart submitochondrial particles, chromatophores from the photosynthetic bacterium Rhodospirillum rubrum and phosphorylating vesicles from P. denitrificans. From the uncoupling obtained with various ions added to the P. denitrificans particles it is concluded that the transmembrane distribution of weak bases and permeant anions permits a determination of the protonmotive force. A flow-dialysis method has been developed to measure the steady-state transmembrane distribution of weak bases and anions in a determination of the protonmotive force. This method successfully overcomes problems which arise with the techniques previously used for these measurements. Under the experimental conditions used to determine the extent of oxidative phosphorylation (the phosphorylation potential) no transmembrane pH gradient was detectable, and the protonmotive force could be accounted for completely by the membrane potential. A method using ion-selective electrodes was developed to provide a continuous determination of this membrane potential. In all 3 systems the proton motive force determined by the above methods was found to be significantly lower than that required by the chemiosmotic hypothesis. A simple modification of the chemiosmotic hypothesis is proposed. This new concept is based on electrodic theory. It is shown to be useful in explaining results reported in the literature (from both photosynthetic and respiratory systems) which appeared to be at odds with the chemiosmotic theory in its usual form.

This study involves the development of a biofilm reactor that supports growth of a deep biofilm on a gas permeable membrane. The reactor solution is not aerated, and oxygen is supplied through the membrane. The reactor is termed a substratum-aerated-biofilm reactor or SAB. With adequate concentrations of electron-donors and electron-acceptors, a deep biofilm grows on the membrane and is comprised of different layers of bacterial activity. The aerobic layers are near the membrane support, while the anaerobic layers are near the biofilm-liquid boundary. In the SAB, the substrate diffuses from the bulk liquid into the biofilm to react. Oxygen diffuses through the membrane into the biofilm. All products likewise are transported by molecular diffusion through the biofilm and into the bulk liquid. The reactors consisted of a reactor wall made of a plexiglass cylinder with the gas permeable membrane supported on a shallow rotating cup. The cup was designed so that the cup and the membrane function as a flat plate. The flat plate was utilized for support of the biological growth, transfer of oxygen, and mixing of the bulk liquid and the gas phase. The experiments were conducted in completely mixed, continuous-flow reactors maintained at 25°C with a hydraulic detention of 8 hours. Pure oxygen was delivered to a gas compartment under the membrane. All reactors were fed a synthetic waste buffered to pH 7.0. The background solution for the feed solution was made from distilled water combined with adequate inorganic nutrients and vitamins. The background solution was supplemented with acetate and ammonia to obtain the desired substrate compositions. Combined nitrification and heterotrophic oxidation activity resulted when the SABs where fed 5 or 10 mg/1 acetate, and 10 mg-N/1 ammonia. Combined nitrification, heterotrophic oxidation, and denitrification resulted with acetate concentration of 20, 40, and 100 mg/1, and 10 mg- N/1 ammonia. Combined heterotrophic oxidation and fermentation resulted with acetate concentration of 800 mg/1, and 10 mg-N/1 ammonia. A series of mass balances were developed to determine the fate of the nitrogen compounds and acetate. These results showed that the flux values for carbon oxidation, nitrification, denitrification, and fermentation are higher than those reported for competing technologies such as rotating biological contactors. / Graduation date: 1990

Includes bibliographical references (p. 62-73).

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 124-143). Also available in print.

Anaerobic bacteria isolated from Kepone-contaminated sediment were screened for their ability to degrade Kepone under anaerobic conditions. The most extensive degradation was produced by denitrifying bacteria grown on benzoate-nitrate medium. In enrichment cultures, Kepone was transformed more extensively than by pure cultures isolated from the enrichments. A gram negative-faculative rod, called K bacterium, transformed 8.8% of the Kepone in a benzoate-nitrate medium in the presence of 2000 ug/ml potassium nitrate under anaerobic conditions. Kepone transformation by K bacterium increased to 21.1% when the potassium nitrate concentration in this medium was 500 ug/ml of medium. Although monohydro-Kepone and dihydro-Kepone were produced as products of the transformation, less than 20% of the transformed Kepone was recovered as these products. Both K bacterium and the enrichment culture transformed [¹⁴C]Kepone. No ¹⁴CO₂, or new radioactive insoluble or soluble products were detected in spent media. Products which were more polar than Kepone, but could not be identified, were observed in GLC chromatograms. K bacterium attached to the Kepone crystals and was pleomorphic during Kepone transformation. These data support the hypothesis that Kepone is transformed when it is used by certain anaerobes as an alternate electron acceptor. / M.S.

Increasing evidence suggests that the oral microbiome is highly relevant to cardiometabolic outcomes. Associations between the oral microbiome and extra-oral outcomes are most commonly hypothesized to result from a chronic inflammatory response to a dysbiotic oral microbiome. However, an alternative mechanism hypothesized to link the oral microbiome to cardiometabolic risk is via the production of nitric oxide, a physiologically important gaseous transmitter. The enterosalivary nitrate-nitrite-nitric oxide pathway of nitric oxide generation is dependent on the presence of nitrate-reducing oral bacteria in the mouth to reduce salivary nitrates to nitrite, which are then swallowed and made systemically bioavailable for further reduction into nitric oxide in the blood vessels and tissues. Thus, this pathway presents a mechanism for oral bacteria to exert a beneficial influence on cardiometabolic health. The overall objective of this dissertation is to advance the understanding of the role of nitrate-reducing oral bacteria in cardiometabolic outcomes in a population setting. This objective was met using three aims. First, a systematic literature review was conducted to identify and assess the associations between nitrate-reducing oral bacteria and insulin resistance, plasma glucose, diabetes, blood pressure and hypertension found in the existing literature. The literature review found no study that explicitly tested the hypothesis of an association between nitrate-reducing oral bacteria and the cardiometabolic outcomes of interest. In addition, there were very few observed associations between nitrate-reducing oral bacteria and these cardiometabolic outcomes, and the findings were inconsistent across studies. Secondly, the associations between nitrate-reducing oral bacteria and insulin resistance, plasma glucose, blood pressure, prediabetes and hypertension were assessed using baseline data from a cohort of diabetes-free participants. Increased levels of oral nitrate-reducing bacteria were associated with lower insulin resistance, plasma glucose and mean systolic blood pressure cross-sectionally, but no associations were found with prediabetes and hypertension. Finally, as dietary nitrate intake influences the level of salivary nitrate in the mouth for the nitrate-reducing oral bacteria to act on, the associations between dietary nitrate and insulin resistance, plasma glucose, blood pressure, prediabetes and hypertension were assessed. No clear associations between higher dietary nitrate intake and the cardiometabolic outcomes were found. However, there was some indication that higher dietary nitrate intake was associated with lower systolic blood pressure. The interaction of dietary nitrate intake with nitrate-reducing oral bacteria was then considered, but no evidence of such interaction was found. Overall, the results of this dissertation suggest that higher levels of nitrate-reducing oral bacteria may confer health benefits across the range of bacterial levels likely observed in human populations. These findings help inform future public health research aimed at utilizing the enterosalivary pathway of nitric oxide generation to improve cardiometabolic health.

Thesis (M.S.)--University of North Carolina Wilmington, 2007. / Includes bibliographical references (leaves: 120-121)

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 53-62). Also available on the World Wide Web.