• Korean Journal of Microbiology
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• v.30 no.2
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• pp.83-87
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• 1992

When the transposon is used as a selectable marker. the cotransduction frequency depends on the selection order of the markers. In this study. we adopted a mathematical approach to explain this phenomenon. At first, the formation of transducing particles were considered in five different configurations. Then the probability functions indicating the possibilities for a marker to be fixed were mathematically formulated on the basis of probability density concept. After actual values and useful assumptions were integrated into the Formula. resulting frequencies from theoretical calculations were compared with actual data. Such analysis let us conclude that the asymmetry in the frequency arose from the lack of homology required for homologous recombination due to the transposon insertion and from the suppression of recombination around the region where the transposon is inserted.

• Korean Journal of Microbiology
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• v.29 no.4
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• pp.215-220
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• 1991

MudJ(Km.lac) operon fusions were used in the identification of osmotic-inducible genetic(osi) loci in Salmonella typhimurium. Expression of osi::lacZ(osi5001, 5027) genes were dramatically induced 39-189 fold when the osmolarity was increased. Seven osm::lacZ genes were constituvely expressed under both low and high osmotic strength. The osi5001::lacZ fusion strains showed the enhanced osmotolerance and the reduced expression of the osi5001::lacZ in the presence of 1mM proline or betaine as osmoprotectants. Four osmotic inducible genetic loci were mapped into 36 (YK531), 44 (YK504), 57 (YK501) and 84 (YK528) map unit by testing the cotransduction frequency.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.201-209
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• 1989

Using Mu dJ(Km lac) operon fusion, several oxygen-regulated genetic loci were identified in Salmonella typhimurium. Nine aerobically inducible(oxi) and thirteen anaerobically inducible(ani) operon fusions were newly identified. Based on the control by oxrA regulatory locus, the ani-lacZ fusions were grouped into two classes: class I loci were regulated by oxrA regulatory locus; class II genes were not affected by this locus. Some of the ani-lacZ fusions had required growth in CAA and LB before they exhibited the inducible phinotype. Most of all ani-lacZ fusions were repressed by nitrate and fumarate. Three of the ani loci were mapped into $59{\pm}0.14$ map unit (YK114), $64{\pm}0.5$ map unit(YK120), and $93{\pm}0.29$ map unit(YK112) by testing the cotransduction frequency, respectively.