Maintenance and genetic stability of vector plasmids pBR322 and pBR325 in Escherichia coli K12 strains grown in a chemostat |
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| Authors: | Dieter Noack, Martin Roth, Rudolf Geuther, Gerhard Mü ller, Katrin Undisz, Christine Hoffmeier Sandor Gá spá r |
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| Affiliation: | (1) Zentralinstitut für Mikrobiologie und experimentelle Therapie, Akademie der Wissenschaften der DDR, Forschungszentrum für Molekularbiologie und Medizin, Beutenbergstrasse 11, DDR-6900 Jena, German Democratic Republic;(2) Institute of Biophysics, Semmelweis Medical University Budapest, H-1088 Budapest, Hungary |
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| Abstract: | Summary The maintenance and genetic stability of the vector plasmids pBR322 and pBR325 in two genetically different Escherichia coli hosts were studied during chemostat cultivation with glucose and ammonium chloride limitation and at two different dilution rates. The plasmid pBR322 was stably maintained under all growth conditions tested. However pBR325 segregated from both hosts preferentially during glucose limitation and at low dilution rate. In addition to this general segregation process a separate loss of tetracycline resistance was observed. The remaining plasmid conferred resistance to ampicillin and chloramphenicol only, without any remarkable alteration of its molecular weight.Cultivation conditions in the chemostat were found that allowed the stable genetic inheritance of both plasmids in the hosts studied. |
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