Vary, Patricia S.
M.S. (Master of Science)
Department of Biological Sciences
Bacterial genetics; Chromosomes; Bacillus megaterium
The purpose of this study was to map the chromosome of Bacillus megaterium. Since it has been stated in the literature that the ribosomal protein region might be more conserved, mutants resistant to antibiotics known toinhibit protein synthesis were therefore isolated. Resistance mutations and auxotrophic mutations in this region were then cotransductionally mapped using phage MP13. The map order by two- and three-factor crosses was D found to be: purA - cml - cysA - rpoB (Rif^(R)) - rpsL (Str^[R]) - gyrA (Nal^[R]) - cysC - purB. The pur and cys mutations were distinguished by growth only on various intermediates, and the cys mutations were also tested for the ability to produce detectable quantities of H₂S. The present loci found in the ribosomal protein region are similar to that of B. subtilis but the cml and cysA loci are inverted. Also, cysB and cysC loci are clustered within the ribosomal protein region in B. megaterium, but are widely dispersed in B. subtilis. Therefore, even in what should have been a conserved region, differences in gene order are still found between the species. Two other linkage groups were also extended. Mutations for serine, methionine, and isoleucine-valine biosynthesis were found to be associated with the previously mapped trp - hisH region. This resulted in a linkage group consisting of 9 loci. In addition, the argA locus was found to be linked to a new leucine mutation in the leu - phe region, as previously demonstrated in B. subtilis. However, several gene linkages observed in B. subtilis could not be demonstrated in B. megaterium, suggesting an overall lack of homology between the two organisms. In this study, 14 new genes were cotransductionally mapped. These, along with previously mapped genes, bring the known genome of B. megaterium to 31 loci mapped into 5 linkage groups.
Bedard, Suzanne L., "Cotransductional mapping in Bacillus megaterium" (1986). Graduate Research Theses & Dissertations. 1990.
vi, 86 pages
Northern Illinois University
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