EFFECTS OF FIVE DIVERSE LIGNOCELLULOSIC DIETS ON DIGESTIVE ENZYME BIOCHEMISTRY IN THE TERMITE Reticulitermes flavipes

摘要

Termites have recently drawn much attention as models for biomass processing, mainly due to their lignocellulose digestion capabilities and mutualisms with cellulolytic gut symbionts. This research used the lower termite Reticulitermes flavipes to investigate gut enzyme activity changes in response to feeding on five diverse lignocellulosic diets (cellulose filter paper [FP], pine wood [PW], beech wood xylan [X], corn stover [CS], and soybean residue [SB]). Our objectives were to compare whole-gut digestive enzyme activity and host versus symbiont contributions to enzyme activity after feeding on these diets. Our hypothesis was that enzyme activities would vary among diets as an adaptive mechanism enabling termites and symbiota to optimally utilize variable resources. Results support our "diet-adaptation" hypothesis and further indicate that, in most cases, host contributions are greater than those of symbionts with respect to the enzymes and activities studied. The results obtained thus provide indications as to which types of transcriptomic resources, termite or symbiont, are most relevant for developing recombinant enzyme cocktails tailored to specific feedstocks. With regard to the agricultural feedstocks tested (CS and SB), our results suggest endoglucanase and exoglucanase (cellobiohydrolase) activities are most relevant for CS breakdown; whereas endoglucanase and xylosidase activities are relevant for SB breakdown. However, other unexplored activities than those tested may also be important for breakdown of these two feedstocks. These findings provide new protein-level insights into diet adaptation by termites, and also complement host-symbiont metatranscriptomic studies that have been completed for R. flavipes after FP, PW, CS, and SB feeding. (C) 2015 Wiley Periodicals, Inc.