Exopolysaccharide assay in Escherichia coli microcolonies using a cleavable fusion protein of GFP-labeled carbohydrate-binding module

A fused protein composed of a carbohydrate-binding module and green fluorescence protein (GFP) was developed to measure the exopolysaccharides (EPShs) present in Escherichia coli microcolonies. The cleavage of the GFP part of this protein using a site-specific protease allowed for the non-invasive and quantitative evaluation of the EPShs. •The GFP-CBM3 fused protein bound to the EPShs in E. coli microcolonies.•The fused protein was released from the microcolonies in a non-destructive manner.•This method could evaluate the EPShs in different amounts of microcolonies.