Electrochemical Microwell Plate to Study Electroactive Microorganisms in Parallel and Real-Time

Microbial resource mining of electroactive microorganism (EAM) is currently methodically hampered due to unavailable electrochemical screening tools. Here, we introduce an electrochemical microwell plate (ec-MP) composed of a 96 electrochemical deepwell plate and a recently developed 96-channel multipotentiostat. Using the ec-MP we investigated the electrochemical and metabolic properties of the EAM models Shewanella oneidensis and Geobacter sulfurreducens with acetate and lactate as electron donor combined with an individual genetic analysis of each well. Electrochemical cultivation of pure cultures achieved maximum current densities (j(max)) and coulombic efficiencies (CE) that were well in line with literature data. The co-cultivation of S. oneidensis and G. sulfurreducens led to an increased current density of j(max) of 88.57 +/- 14.04 mu A cm(-2) (lactate) and j(max) of 99.36 +/- 19.12 mu A cm(-2) (lactate and acetate). Further, a decreased time period of reaching j(max) and biphasic current production was revealed and the microbial electrochemical performance could be linked to the shift in the relative abundance.

Automated summary

This study introduces a new electrochemical microwell plate for investigating the electrochemical and metabolic properties of electroactive microorganisms, allowing for experiments in both pure culture and co-culture modes. Results show that different electron donors have an impact on current density and coulombic efficiency, and the microbial electrochemical performance is correlated with the shift in microbial relative abundance.