Browsing by Author "Jones, David T"

Now showing 1 - 8 of 8
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    The cloning and characterisation of an endoglucanase and an endoxylanase from Clostridium acetobutylicum in Escherichia coli
    (1988) Zappe, Harold; Woods, David R; Jones, David T
    Clostridium acetobutylicum P262 is an endospore forming Gram-positive obligate anaerobe which has been used for the industrial production of acetone and butanol. Strains of C. acetobutylicum have been reported to exhibit some activity towards cellulosic and hemicellulosic substrates. The aim of this thesis was to establish a genebank of C. acetobutylicum P262 DNA in Escherichia coli and to isolate and characterise genes encoding enzymes which show activity towards hemicellulose and cellulose.
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    DNA repair in Bacteroides fragilis Bf-2
    (1987) Abratt, Valerie Rose; Woods, David R; Jones, David T
    Repair deficient mutants of Bacteroides fragilis have been isolated in order to study the responses of this organism to various DNA damaging agents at the physiological and molecular levels. Two types of mutants were isolated by ethyl methane sulphonate mutagenesis of B.fragilis followed by selection for sensitivity to mitomycin C. One mutant (UVS9) showed sensitivity to both mitomycin C and far-UV irradiation. The other (MTC25) was more sensitive to mitomycin C than UVS9, but showed wild-type resistance to UV radiation. Both mutant strains had wild-type resistance to methyl methane sulphonate.
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    Effects of far ultra-violet radiation and oxygen on macromolecular synthesis and protein induction in Bacteroides fragilis Bf-2
    (1984) Schumann, Jacoba Petronella; Woods, David R; Jones, David T
    This thesis deals with a study of the effects of far-UV radiation, oxygen and hydrogen peroxide on macromolecular synthesis and viability in the obligate anaerobe, Bacteroides fragilis, as well as the specific proteins induced in this organism by these different DNA damaging agents.
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    Expression of a clostridium acetobutylicum endoglucanase and an endoxylanase in saccharomyces cerevisiae
    (1989) Lewis, Elizabeth A; Woods, David R; Jones, David T
    S. cerevisiae is widely used in industrial processes, in particular ethanol production. The aim of this study was to examine the feasability of cloning lignocellulase genes into yeast. These enzymes could possibly extend the substrate range of S. cerevisiae, thereby possibly making the process of ethanol production more cost effective.
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    Fermentation studies on Clostridium acetabutylicum
    (1982) Van der Westhuizen, André; Woods, David R; Jones, David T
    The initial aim of this work was to develop a laboratory system for the study of the ABE fermentation under laboratory conditions. The development of defined and simple laboratory inoculation and build-up procedures for the ABE process was investigated. A defined spore preparation in distilled water gave solvent yields comparable to the yields obtained in the commercial ABE process. A laboratory inoculation procedure was developed which avoided the lengthy culture build-up procedures presently utilised. An investigation into solvent production by Clostridium acetobutylicum in clostridial basal medium (CBM) , reinforced clostridial medium (RCM) , Leung and Robson media was undertaken with the aim of developing a partially defined laboratory medium which produced solvent yields comparable to the molasses fermentation medium (MFM). The solvent yields obtained in the partially defined laboratory media were substantially lower than those obtained in MFM. It became apparent that the initial aim of trying to identify and manipulate a few key factors to give better solvent yields would not be easily attained. Both the solvent levels and the overall pattern of cell development were markedly different in the various laboratory systems. In view of these differences, a more detailed investigation of the growth patterns, morphological and physiological changes were undertaken.
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    Microbial solvent formation revisited by comparative genome analysis
    (BioMed Central, 2017-03-09) Poehlein, Anja; Solano, José D M; Flitsch, Stefanie K; Krabben, Preben; Winzer, Klaus; Reid, Sharon J; Jones, David T; Green, Edward; Minton, Nigel P; Daniel, Rolf; Dürre, Peter
    Background: Microbial formation of acetone, isopropanol, and butanol is largely restricted to bacteria belonging to the genus Clostridium. This ability has been industrially exploited over the last 100 years. The solvents are important feedstocks for the chemical and biofuel industry. However, biological synthesis suffers from high substrate costs and competition from chemical synthesis supported by the low price of crude oil. To render the biotechnological production economically viable again, improvements in microbial and fermentation performance are necessary. However, no comprehensive comparisons of respective species and strains used and their specific abilities exist today. Results: The genomes of a total 30 saccharolytic Clostridium strains, representative of the species Clostridium acetobutylicum, C. aurantibutyricum, C. beijerinckii, C. diolis, C. felsineum, C. pasteurianum, C. puniceum, C. roseum, C. saccharobutylicum, and C. saccharoperbutylacetonicum, have been determined; 10 of them completely, and compared to 14 published genomes of other solvent-forming clostridia. Two major groups could be differentiated and several misclassified species were detected. Conclusions: Our findings represent a comprehensive study of phylogeny and taxonomy of clostridial solvent producers that highlights differences in energy conservation mechanisms and substrate utilization between strains, and allow for the first time a direct comparison of sequentially selected industrial strains at the genetic level. Detailed data mining is now possible, supporting the identification of new engineering targets for improved solvent production.
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    Molecular genetic characterization of two solvent pathway dehydrogenases from Clostridium Acetobutylicum
    (1989) Youngleson, Jonathan Sinclair; Woods, David R; Jones, David T
    Clostridium acetobutylicum P262 is an endospore-forming Gram-positive anaerobic bacterium, which has been used for the industrial production of acetone and butanol from carbohydrate substrates. This study forms part of a wider research effort into the genetics and molecular biology of C. acetobutylicum, which has as an ultimate goal the commercial improvement, and a fundamental understanding of the ABE fermentation. The aim of this study was to isolate and characterize genes involved in solventogenesis. The cloning, expression and characterization of the terminal solventogenic butanol dehydrogenase gene ( adhl), and the central pathway β-hydroxybutyryl-CoA dehydrogenase gene (hbd), which form part of a but operon are described.
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    A reassessment of the production of acetone and butanol by Clostridium acetobutylicum in continuous culture
    (1987) Clarke, Kim Gail; Hansford, Geoffrey Spearing; Jones, David T
    The production of acetone and butanol by Clostridium acetobutylicum P 262 was studied in continuous culture under conditions where the nutrients were present in excess of the requirements and the cell growth was limited by the products formed during the fermentation. This system differs from most continuous culture systems used to obtain solvent production where the limitation of a specific nutrient was utilised to limit the cell growth.