Detection and quantitation of cellulase by Congo red staining of substrates in a cup-plate diffusion assay

A simple, inexpensive, and sensitive cellulase assay which allows simultaneous enzyme quantitation for many samples has been developed. Radial diffusion of enzyme into substrate incorporated in an agar gel produces zones of hydrolysis which can be visualized by staining undegraded substrate with Congo red dye. Comparisons were made between this and other commonly used cellulase assays based on accuracy, sensitivity, and ease of use.