Plant polysaccharides represent a virtually unlimited feedstock for the generation of biofuels and other commodities. However, the extraordinary recalcitrance of plant polysaccharides toward breakdown necessitates a continued search for enzymes that degrade these materials efficiently under defined conditions. Activity-based protein profiling provides a route for the functional discovery of such enzymes in complex mixtures and under industrially relevant conditions. Here, we show the detection and identification of β-xylosidases and endo -β-1,4-xylanases in the secretomes of Aspergillus niger , by the use of chemical probes inspired by the β-glucosidase inhibitor cyclophellitol. Furthermore, we demonstrate the use of these activity-based probes (ABPs) to assess enzyme–substrate specificities, thermal stabilities, and other biotechnologically relevant parameters. Our experiments highlight the utility of ABPs as promising tools for the discovery of relevant enzymes useful for biomass breakdown.

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Corn hull from a wet milling process contains 23% starch, 38% hemicellulose, 11% cellulose, 11.8% protein, 1.2% ash, and minor constituents. The starch fraction can be completely hydrolyzed by glucoamylase after the hull is heated with steam for 5 min. The hemicellulose fraction of destarched hull can be further hydrolyzed by sulfuric acid with a solid‐acid ratio of about 30 to 1 and a liquidsolid ratio of about 3 to 1. A process based upon the above findings yields 49 lb. of fermentable sugar (xylose + glucose) per 100 lb. of dry corn hull. The product does not inhibit yeast fermentation.

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