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Background The environment of a previous novel blaCTX-M gene is investigated in the current study. Sequencing the boundaries of the gene revealed the presence of a mosaic genetic element containing a misc. feature (referring to the novel blaCTX-M). The sequence of the mosaic element is deposited to GenBank (accession no. MT215579). Methods Reverse transcription PCR and production of β-lactamases by nitrocefin colorimetric β-lactamase activity assay were used to evaluate the expression and production of β-lactamases in the Escherichia coli strain EC1091. Results When investigating the β-lactamase production in EC1091, the truncated gene showed variable enzyme productions. The production was only maintained under sub-inhibitory concentrations of novobiocin. The production of β-lactamases reported a (1.2–2.2) fold increase compared to basal treatments. The obtained results document for the first time the interference of a coumarin antibiotic in the expression of β-lactamases suggesting a control mechanism for the truncated blaCTX-M gene. High similarities were found by BLASTN search between the sequence of the mosaic element to certain determinants in pC15.1a and AR_0015 plasmids. Conclusion Further investigation of the truncated gene or its homologs in other genomes may provide valuable data in terms of the evolution, resistance, and control mechanisms of bla genes. |
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