Thesis (M.S.)--Ohio University, November, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 74-83).

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 174-176). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 174-176). Also available on the Internet.

Thesis (M.S.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Alfred B. Cunningham. Includes bibliographical references (leaves 49-53).

Thesis (Ph.D.) - University of St Andrews, March 2008.

Biotechnology of sulphate reducing bacteria has developed rapidly in recent years with the recognition of their extensive and diverse biocatalytic potential. However, their application in a number of areas has been constrained due to problems including poor cell retention within the continuous bioprocess reactor environment, and contamination of the treated stream with residual organic feed components and cell biomass. These problems have so far excluded the application of biological sulphate reduction in the treatment of ‘clean’ inorganic waste streams where components such as sulphate, acidity and heavy metal contamination require treatment. This study investigated the effective immobilisation of sulphate reducing bacterial cultures and proposed that the disarticulation of the electron donor and carbon source supply using such systems would create the basis for their application in the treatment of ‘clean’ inorganic waste streams. A functional and stable sulphate reducing culture was selected and following evaluation using a number of techniques, was immobilised by encapsulation within a calcium-alginate-xanthum gum membrane to give robust capsules with good sulphate reduction activity. The concept of disarticulation was investigated in a swing-back cycle where the carbon source was excluded and the electron donor supplied in the form of hydrogen gas in a continuous up-flow capsule-packed column reactor. Following a period of operation in this mode (4-12 days), the system was swung back to a carbon feed to supply requirements of cell maintenance (2-3 days). Three types of synthetic ‘clean’ inorganic waste stream treatments were investigated, including sulphate removal, neutralisation of acidity and heavy metal (copper and lead) removal. The results showed: • Sulphate removal at a rate of 50 mg SO₄²⁻L/day/g initial wet mass of capsules during three 4-day cycles of electron donor phase. This was comparable to the performance of free cell systems; • Neutralisation of acidity where influent pH values of 2.4 and 4.0 were elevated to above pH 7.5; • Copper removal of 99 and 85 % was achieved with initial copper concentrations of 2 and 60 mg/L respectively; • Percentage lead removal values of 49 and 78 % were achieved; This first report on the application of the concept of capsular immobilisation and disarticulation in the treatment of ‘clean’ inorganic waste streams will require future studies in order to extend the development of the full potential of the concept.

Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2008. / Lowell, Robert, Committee Chair ; Newman, Andrew, Committee Member ; Peng, Zhigang, Committee Member.

Compaction of DNA into chromatin is an important feature of every living cell. This compaction phenomenon is brought about and maintained by a variety of DNA binding proteins, which have evolved to suit the specific needs of the different cell types spanning the three kingdoms of life; the eukaryotes, prokaryotes and archaea. Sulfolobus solfataricus, a member of the crenarchaeal subdivision of the archaea, has two prominent DNA binding proteins known as Alba (1&2) and Sso7d. Alba1 is acetylated in vivo at two positions and this modification lowers its’ affinity for binding DNA. Acetylation levels impact many cellular processes and in higher organisms play a critical role in the development of many cancers and other diseases. This thesis documents the finding and characterisation of the N-terminal acetyltransferase (ssArd1) of SsoAlba1, based on its’ sequence homology to the catalytic subunits Ard1, Nat3 and Mak3 belonging to the larger eukaryal Nat complexes NatA, NatB and NatC, respectively. Mutagenesis studies revealed that ssArd1 preferentially acetylates N-termini bearing a serine or alanine residue at position 1 (after methionine cleavage). It is also capable of acetylating other proteins with very different physical structures. These findings allow classification of ssArd1 as a promiscuous acetyltransferase belonging to the Gcn5-N-acetyltransferase (GNAT) superfamily. The active site of the enzyme was examined through mutagenesis studies, revealing that the mechanism of acetylation is likely to proceed through a direct acetyl transfer involving a tetrahedral intermediate. Structural studies provided some insight into the molecular structure of ssArd1.

The movement towards a more sustainable energy economy may require not only the generation of cleaner fuel sources, but the conversion of waste streams into value-added products. Phototrophic purple non-sulfur bacteria are capable of metabolizing VFAs (volatile fatty acids)and generate hydrogen as a byproduct of nitrogen fixation using energy absorbed from light. VFAs are easily produced from dark anaerobic fermentation of food, agricultural, and municipal wastes, which could then be fed into photobioreactors of purple bacteria for hydrogen production. The process of photofermentation by purple bacteria for hydrogen production remains attractive due to the capability of reaching high substrate conversions under mild operating conditions, but increasing the efficiency of converting light energy into hydrogen remains challenging. Purple bacteria cannot utilize the entire solar spectrum, and the dominant region of absorption lies in the near-infrared region above 800 nm. In this work, the model purple non-sulfur bacteria Rhodopseudomonas palustris was used to study different strategies to increase light utilization and hydrogen production. Near-infrared LED arrays were selected to match the target bacteriochlorophyll absorption range, and were tested to be used as a sole illumination source for photofermentation. Additionally, plasmonic nanoparticles with resonant frequencies matching bacterial absorbance were added in solution to increase light utilization through scattering and near field electric enhancement effects at intensities around 100 W/m2 . Both of these approaches proved to increase cellular growth rate and hydrogen production, which opens the door to utilizing more advanced photonic structures for use in bacterial phototrophic processes.

Biological hydrogen production is a renewable, carbon-neutral and clean route for hydrogen production. Purple non-sulfur (PNS) bacteria have the ability to produce biohydrogen via photofermentation process. The type of the bacterial strain used in photofermentation is known to have an important effect on hydrogen yield. In this study, the effect of different co-cultures of PNS bacteria on photofermentation process was investigated in search of improving the hydrogen yield. For this purpose, growth, hydrogen production and substrate utilization of single and co-cultures of different PNS bacteria (R. capsulatus (DSM 1710), R. capsulatus hup- v (YO3), R. palustris (DSM 127) and R. sphaeroides O.U.001 (DSM 5864)) were compared on artificial H2 production medium in 150 mL photobioreactors under continuous illumination and anaerobic conditions. In general, higher hydrogen yields were obtained via co-cultivation of two different PNS bacteria when compared with single cultures. Further increase in hydrogen yield was observed with co-cultivation of three different PNS bacteria. Co-cultures of two different PNS bacteria have resulted in up to 1.4 and 2.1 fold increase in hydrogen yield and hydrogen productivity. Whereas co-cultures of three different PNS bacteria have resulted in up to 1.6 and 2.0 fold increase in hydrogen yield and hydrogen productivity compared to single cultures. These results indicate that, defined co-cultures of PNS bacteria produce hydrogen at a higher yield and productivity, due most probably to some synergistic relationship. Further studies regarding the physiological and molecular changes need to be carried out for deeper understanding of the mechanism of hydrogen production in co-cultures.