Design and control of extrachromosomal elements in methylorubrum extorquens AM1

Methylorubrum extorquens AM1 is used as a model organism for the study of methylotrophy. It’s unique ability to grow on C1 carbon sources (like methanol or formate) makes it an increasingly relevant organism for biotechnology in a methanol- and formate-based bioeconomy. Up to date, several value-added chemicals (i.e. mevalonate, α-humulene, 3-hydroxypropionate, and 1-butanol) have been produced in this organism, but further development requires a more complete set of genetic tools. For example, there is a lack of dynamic control of gene expression and in the availability and control over extrachromosomal genetic elements; there is only one plasmid that has been reported to replicate in M. extorquens without causing severe growth defects, and transformation efficiency for genomic integration still remains to be optimized.
This paper describes the development of a set of inducible, orthogonal promoters of different strengths aimed at expanding the limited genetic toolbox of M. extorquens. The authors have also tested new repABC regions (small regions that drive the vertical transmission of secondary replicons) to establish a set of extrachromosomal elements (“mini-chromosomes”) that are faithfully inherited by daughter cells and compatible with each other. This work provides the tools for the extensive genetic engineering of M. extorquens AM1, opening new ways to unleash the metabolic and biotechnological potential of this organism for future applications. For more information, check out the full paper now available online.

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