A pBBR1-based vector with IncP group plasmid compatibility for Methylorubrum extorquens

L. Pöschel, E. Gehr, M. Buchhaupt

DOI: https://doi.org/10.1002/mbo3.1325



The pBBR1 derivative pMis1_1B, which was characterized in this study, represents a novel plasmid for Methylorubrum extorquens, which is compatible with the widely used pCM system. The growth defect caused by the plasmid was found to be enhanced by the presence of a pCM plasmid, but cotransformation could be demonstrated to be possible.

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Plasmids are one of the most important genetic tools for basic research and biotechnology, as they enable rapid genetic manipulation. Here we present a novel pBBR1-based plasmid for Methylorubrum extorquens, a model methylotroph that is used for the development of C1-based microbial cell factories. To develop a vector with compatibility to the so far mainly used pCM plasmid system, we transferred the pBBR1-based plasmid pMiS1, which showed an extremely low transformation rate and caused a strong growth defect. Isolation of a suppressor mutant with improved growth led to the isolation of the variant pMis1_1B. Its higher transformation rate and less pronounced growth defect phenotype could be shown to be the result of a mutation in the promotor region of the rep gene. Moreover, cotransformation of pMis1_1B and pCM160 was possible, but the resulting transformants showed stronger growth defects in comparison with a single pMis1_1B transformant. Surprisingly, cotransformants carrying pCM160 and a pMis1_1B derivative containing a mCherry reporter construct showed higher fluorescence levels than strains containing only the pMis1_1B-based reporter plasmids or a corresponding pCM160 derivative. Relative plasmid copy number determination experiments confirmed our hypothesis of an increased copy number of pMis1_1B in the strain carrying both plasmids. Despite the slight metabolic burden caused by pMis1_1B, the plasmid strongly expands the genetic toolbox for M. extorquens.

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