Screening for Cellulolytic Plant Enzymes Using Colorimetric and Fluorescence Methods

This is a post-peer-review, pre-copyedit version of an article published in The Plant Cell Wall Methods and Protocols. The final authenticated version is available online at: https://doi.org/10.1007/978-1-0716-0621-6. Cellulolytic activity can be measured using a variety of methods, the choice of which depends on the raw material and goals. An inexpensive, rapid, and reliable method, suitable for plants and other sources alike, is based on digestion of the easily degradable soluble cellulose derivative carboxymethylcellulose (CMC). Direct detection of CMC digestion by cellulolytic activity is based on the “negative staining principle,” where undigested CMC is stained with appropriate colorimetric or fluorescent stains, while CMC exposed to digestion by cellulase shows a reduction in staining intensity. The reduction is proportional to the enzyme activity and is not influenced by endogenous levels of glucose in the sample, making this method applicable for a wide variety of samples, including plant material