Aquatic invertebrate’s Carbohydrate-binding module assists environmental cellulase to immobilize in wetland sediments

Carbohydrate-binding modules (CBMs) are non-catalytic protein domains that bind to carbohydrates, and have been well studied in microorganisms. Endogenous CBMs aquatic invertebrates, however, not yet identified, little is known about their ecological significance wetland environments. Using an approach of characterizing a recombinant CBM (CjCel9A) from brackish bivalve, Corbicula japonica, this work identified CjCel9A-CBM’s cellulose-binding activity. Scatchard plot analysis the study CjCel9A-CBM binding α-cellulose showed high corresponding partitioning coefficient (Kr) 20.33, indicating affinity for cellulose. In addition, tolerated ion concentration buffer system, consistent with C. japonica’s adaption Moreover, immuno-scanning electron microscopy (immuno-SEM) suggested binds unevenly, which was further determined be caused by its higher crystalline cellulose (Cellulose I, mostly seen plant leaves). Together, these findings suggest capable immobilizing associated catalytic domain on environmental (i.e., fallen leaves) sediments. Most importantly, they could provide reasonable answer question recognized broadly ecologists, namely, why many sediments constant cellulase activities, although being washed almost every day.