Vary, Patricia S.
M.S. (Master of Science)
Department of Biological Sciences
Bacillus megaterium; Plasmids; Bacterial genetics
Bacillus megaterium strain QM B1551 has recently been analyzed for its plasmid content and was found to contain at least 11% of the total DNA in the form of plasmid DNA. There are seven size classes of plasmids ranging from 3.5-109 megadaltons (Md). It was the purpose of this study to analyze these plasmids for any possible gene functions. The wild type strain was cured of some of its plasmids with ethidium bromide, sodium dodecyl sulfate, or novobiocin. These cured strains were compared with wild type for the loss of function. Cells were tested for growth on carbon sources citrate, xylose, sucrose, maltose, mannitol, and for protease, phospholipase, and amylase. No difference from wild type was observed for any of the cured strains. The ability to degrade unusual compounds was also examined by growing wild type and cured strains in various concentrations of naphthalene, camphor, toluene, or xylene. Again, no difference between wild type and the cured strains was observed. The strains tested could not utilize these compounds as carbon sources but could grow in their presence. Over 65% of the cured strains were, however, negative for megacin production. B. megaterium produces a bacteriocin which resembles megacin C. This megacin was further characterized and the optimum conditions for its production were defined. It was produced during logarithmic growth and was non-inducible with low levels of ultraviolet radiation. It was precipitated with 60-80% ammonium sulfate and lost activity when heated, suggesting it was a protein. The megacin might be a wall component since protoplasts showed no megacin activity, even after lysis. Attempts were made to correlate megacin production with a particular plasmid but were unsuccessful. As a secondary plasmid analysis project, the smaller plasmid of QM B1551 was digested with restriction endonucleases to determine whether it might contain unique restriction sites, and therefore be useful as a cloning vector. The 3.5 Md plasmid was found to have at least one unique restriction site, for the enzyme Hae III. It therefore has potential as a Gram-positive cloning vector.
Weiland, Katherine Lee, "Plasmid analysis of megacin negative strains of Bacillus Megaterium QM B1551" (1985). Graduate Research Theses & Dissertations. 4412.
v, 108 pages
Northern Illinois University
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