A comprehensive inventory of lignocellulolytic enzymes in the wood-feeding cockroach Cryptocercus punctulatus

As fossil fuels are being depleted, much attention has turned to the most abundant carbohydrate energy resources on Earth, lignocelluloses, a naturally occurring complex of plant-derived materials that includes hydrophilic sugar polymers cellulose and hemicellulose, and a hydrophobic organic “glue”- lignin. However, to release the solar energy stored within, an array of enzymes referred to as lignocellulases are required to disassociate a matrix of cellulose, hemicelluloses, pectins, lignin, and glycosidic linkages. Wood-feeding Dictyopterans including termites and woodroaches are the most efficient lignocellulose-processing bioreactors existing in nature, and have intrigued scientists for decades because of their unique capability of breaking down seemingly recalcitrant lignocelluloses rapidly. The pressing needs for bioenergy and biomass conversion have redirected termite research to focus more on lignocellulose digestion and degradation. However, there is virtually no information available on the termite sister group, a wood-feeding cockroach Cryptocercus which has more diversified lignocellulolytic symbionts than termites. To search for novel lignocellulolytic enzymes, we initiated a large-scale transcriptome/metatranscriptome sequencing project focusing on the digestive tract of wood-feeding cockroach, Cryptocercus punctulatus. Comparative transcriptomic/metatranscriptomic analyses of genes from Cryptocercus and termites allow us to identify the “core” enzymes that drive the lignocellulose-processing bioreactors of Dictyopterans (termite and woodroach).