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Biochemical characterization of E. coli transconjugants with plasmids derived from Klebsiella pneumoniae
Abstract:
Sixty-three strains of E. coli transconjugants derived from E. coli K12 J62-1 containing plasmids derived from Klebsiella pneumoniae, were examined for the presence of phenotypic markers other than antibiotic resistance. This investigation was carried out using API 50CHE and API ZYM tests. Beta-glucosidase was found in 63/63 J62-1 transconjugants. Dulcitol dehydrogenase was present in 92.1% while beta-galactosidase was present in 70% of transconjugants. None of the three enzymes were present in the recipient. Dulcitol dehydrogenase was present only in the transconjugants and is absent from the donors and recipient. The transconjugants, cured of their antibiotic resistant plasmids retained dulcitol dehydrogenase activity. The Klebsiella donors were not cured of antibiotic resistance by the curing process.
Insights
E. coli transconjugants acquired new traits from Klebsiella pneumoniae, including dulcitol dehydrogenase activity. This enzyme remained even after removing antibiotic resistance plasmids, indicating stable genetic transfer.
Area of Science:
- Microbiology
- Genetics
Background:
- Escherichia coli (E. coli) K12 J62-1 is a common laboratory strain.
- Klebsiella pneumoniae can transfer genetic material, including antibiotic resistance plasmids, to E. coli.
- Phenotypic characterization of transconjugants is crucial for understanding gene expression and transfer.
Purpose of the Study:
- To investigate the presence of non-antibiotic resistance phenotypic markers in E. coli transconjugants.
- To determine if specific enzyme activities are transferred from Klebsiella pneumoniae to E. coli.
- To assess the stability of transferred traits, such as dulcitol dehydrogenase activity.
Main Methods:
- Utilized API 50CHE and API ZYM test kits for phenotypic analysis.
- Generated E. coli K12 J62-1 transconjugant strains containing plasmids from Klebsiella pneumoniae.
- Performed plasmid curing experiments to assess trait stability.
Main Results:
- All E. coli transconjugants (63/63) expressed beta-glucosidase.
- Dulcitol dehydrogenase was detected in 92.1% of transconjugants, while beta-galactosidase was present in 70%.
- Dulcitol dehydrogenase activity was observed in transconjugants but not in the recipient or donor strains, and persisted after plasmid curing.
Conclusions:
- The transfer of Klebsiella pneumoniae plasmids to E. coli results in the acquisition of novel enzymatic activities.
- Dulcitol dehydrogenase is a reliable marker for successful plasmid transfer from Klebsiella pneumoniae to E. coli.
- The genetic determinants for dulcitol dehydrogenase activity are stably maintained in E. coli transconjugants, independent of antibiotic resistance genes.