E-Cuvettes parallelize electrochemical and photometric measurements in cuvettes and facilitate applications in bio-electrochemistry

Abstract

Parallelized and automated screening systems are widely used in process development and optimization in bioelectrochemical applications. This includes the rapid testing and measuring of electrochemical potentials, electrical current densities, mediators, buffers, and biocatalysts. While different methods for screening electroactive organisms have been developed and evaluated in recent studies, there is no parallel device available so far, that can imitate a gas-fed and mediator-based bioelectrochemical system. Here we propose a device that is based on common 3.5 mL cuvettes as reaction vessels that implement commercially available screen-printed electrodes. In combination with a photometer fitted with an autosampler, the device measures the cell density as well as the mediator redox state online. The design enables cultivation times up to 120 h in 8 parallel e-Cuvettes and was validated by cultivating the well-characterized electroactive strain Pseudomonas putida KT2440 with 1 mM K3[Fe(CN)6] as redox mediator. With this setup, high current densities up to 113.42 ± 22.09 μA cm−2 were obtained. Via e-Cuvettes, setup times can be shortened from days to hours in comparison to established bioelectrochemical reactor systems, while maintaining sufficient liquid volume to allow for sampling of the culture broth.