Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2010
Publication Date: 11/1/2010
Publication URL: http://ddr.nal.usda.gov/handle/10113/49924
Citation: Willis, J.D., Klingeman, W.E., Oppert, C., Oppert, B.S., Jurat-Fuentes, J.L. 2010. Characterization of cellulolytic activity from digestive fluids of Dissosteira carolina (Orthoptera: Acrididae). Comparative Biochemistry and Physiology. 157(3):267-272. doi: http://dx.doi.org/10.1016/j.cbpb.2010.06.012. Interpretive Summary: Little is know about insect cellulases, enzymes that break down cellulose in plant tissues. In a previous study, we found high levels of cellulase activity in a grasshopper. In this study, we found four distinct cellulase activities expressed throughout the developmental stages in the head and gut of the grasshopper. This research will enable the development of novel control methods for insects that target cellulase enzymes as well as provide enzymes that may be used in bioindustrial degradation processes to produce biofuels.
Technical Abstract: Previous screening of head-derived and gut fluid extracts of Carolina grasshoppers, Dissosteira carolina (L.), revealed relatively high activity against cellulase substrates when compared to other insect groups. In this work we report on the characterization and identification of enzymes involved in cellulolytic activity in digestive fluids of D. carolina. In zymograms using carboxymethylcellulose (CMC) as substrate, we detected four distinct cellulolytic protein bands in D. carolina gut fluids, common to all developmental stages. These cellulolytic enzymes were localized to foregut and midgut regions of the D. carolina digestive tract. Cellulases were purified from D. carolina head and gut fluid extracts by liquid chromatography to obtain N-terminal amino acid sequence tags. Database searches with sequence tags from head fluids indicated high similarity with invertebrate, bacterial, and plant ß-1,4-endoglucanases, while no homologues were identified for the gut-derived protein. Our data demonstrate the presence of cellulolytic activity in the digestive system of D. carolina and suggest that cellulases of endogenous origin are present in this organism. Considering that this grasshopper species is a pest of grasses, including switchgrass that has been suggested as a bioethanol feedstock, characterization of insect cellulolytic systems may aid in developing applications for plant biomass biodegradation for biofuel production.