Towards enabling engineered microbialelectronic systems: RK2-based conjugal transfer system for Shewanella synthetic biology

Synthetic biology has been traditionally associated with electronics through the application of circuit design concepts towards the genetic engineering of microbes. Due to recent advances in the understanding of extracellular electron transfer in the bacterium Shewanella oneidensis (Shewanella), synthetic biology advances now have the potential of being used towards electronics applications. Towards this end, there is a need for tools that enable the systematic optimisation of genetic circuits in Shewanella. With the introduction of an RK2 origin of transfer cassette, we show that a modular plasmid system constructed prior for synthetic biology efforts in the bacterium Escherichia coli (E. coli) can be ported to Shewanella. In the process, it is also shown that different replication origins can be maintained in Shewanella and that multiple-plasmid strains can be realised in the bacterium. The results suggest that parts accumulated from E. coli synthetic biology efforts over the past decade and a half may be able to be ported to Shewanella, enabling the future engineering of systems where microbes interface with electronics (e.g. biosensors).