Electrochemical screening of recombinant protein solubility in Escherichia coli using scanning electrochemical microscopy (SECM)

A microbial array chip with collagen gel spots entrapping living Escherichia coli (E. coli) DH5α was applied for the screening of recombinant protein solubilities. The α-fragment of β-galactosidase (βGal) was fused to the target protein, namely, maltose-binding protein (MBP), to monitor the solubility of MBP. Scanning electrochemical microscopy (SECM) was used to detect the release of p-aminophenol from E. coli cells catalyzed by intracellular βGal. Comparison of the SECM-based method with the Western blotting-based method indicated that the current response obtained using SECM increased with an increase in the βGal activity and therefore, with the soluble fraction of MBP in the host cells.