Publication Date


Document Type


Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Plasmids; Thermophilic bacteria


An analysis of the various strains/species of Thermus. with respect to the number and molecular weights of their native plasmids was performed. Mini-plasmid preparations of Thermus cultures were analyzed by way of one-dimensional and two-dimensional agarose gel electrophoresis in order to determine the resident number of plasmids present in each of these strains/species. Plasmids were also analyzed for their relative mobilities and log/log plots of relative mobilities vs. molecular weights were constructed to determine the molecular weights of the newly characterized covalently closed circular plasmid forms. From these analyses, the following plasmid complements were determined: Thermus strain T-2, one plasmid (15.2 mdal); X*. filiformis. 9 plasmids (3.1, 3.5, 4.2, 5.7, 6.7, 8.0, 11.0, 13.0, 42.0 mdal); T^_ caldophilus, T. lacteus and T^ ruber were found to lack plasmid DNA. The presence of a 6.7 mdal plasmid was confirmed in T^ flavus AT62, and the presence of a second 23.0 mdal plasmid was suggested. Culture conditions and procedural techniques were optimized with regard to bulk plasmid isolation and spheroplast generation efficiency for utilization in future transformation experiments. Curing studies were performed to ascertain the location of the genetic element(s) coding for bacteriocin production in Thermus rubens. Novobiocin was employed in conjunction with a reduced growth temperature to induce curing. A number of mutants were generated, however, when the plasmid content of these mutants was analyzed, all were found to still contain the 64 mdal plasmid. Therefore, a plasmid or chromosomal coding location was unable to be established. These mutants were frozen for future genetic analyses.


Includes bibliographical references (pages 103-109)


vii, 111 pages




Northern Illinois University

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