The LIMES project, funded by the German Federal Ministry of Education and Research under the grant number 13XP5152A, ran from 1 September 2021 to 31 December 2022 at the Technical University of Hamburg’s Institute for Technical Microbiology. Its goal was to create engineered living materials that combine the exoelectrogenic bacterium *Shewanella oneidensis* with electrically conductive DNA polymers, enabling bioelectrochemical synthesis of riboflavin while allowing precise control over biofilm thickness through inducible DNase activity. The project was carried out in close collaboration with the microfluidics company Bartels and involved internal groups led by Gescher and Niemeyer, who also provided training for two employees from the Niemeyer group.

On the technical side, the team successfully engineered a *S. oneidensis* strain in which all native DNase genes were deleted, producing a robust biofilm phenotype that could be monitored continuously by automated optical coherence tomography. The deletion strain exhibited a markedly reduced biofilm volume compared with the parental strain that retained DNase activity, confirming the role of extracellular DNA in biofilm formation and electrical conductivity. A single DNase gene was then reintroduced under control of a rhamnose‑inducible promoter, creating a system capable of targeted extracellular DNA hydrolysis; however, experiments with synthetic DNA on the cell surface could not be completed within the project timeframe. An overexpression plasmid was constructed to boost riboflavin production, targeting at least a two‑fold increase, although the final yield was not reported in the final report. The microfluidic bioelectrochemical system was expanded with a multifunctional sampling unit that can distribute culture medium from 12 independent channels into user‑defined sample vessels. A custom, programmable control software was developed to schedule sampling and pumping operations, enabling fully automated operation of the platform. The integration of this sampling technology was completed by month two of the project, and the platform was successfully handed over and commissioned by the end of the project.

The project also built on earlier work that produced conductive DNA composites incorporating carbon nanotubes and silica nanoparticles via enzymatic polymerisation. These composites provide a conductive scaffold for electron transfer from *S. oneidensis* to an anode, while the programmable DNA backbone allows for controlled release and degradation of extracellular DNA. The LIMES effort demonstrated that such a hybrid material can be coupled to a microfluidic BES, but the continuous process operation and the full riboflavin production target could not be realised within the 18‑month period. Nevertheless, the development of a DNase‑controlled strain, a riboflavin‑overexpressing plasmid, and an automated microfluidic platform represents a significant step toward engineered living materials for bioelectrochemical synthesis. The successful workshop on bioelectrochemical systems and the exchange visits between the Gescher and Niemeyer groups further strengthened the collaborative framework of the project.