Saccharification of Agricultural Lignocellulosic Feedstocks by Endogenous and Symbiotic Cellulases from the Subterranean Termites

This study investigated the protein fraction-level in vitro and in vivo saccharification potential to biofuel producing feedstocks by the guts of two geographically different termite species. The focus was (i) to measure saccharification potential of feedstocks with respect to control diet (filter paper) by termites’ gut of Reticulitermes flavipes and Heterotermes indicola , (ii) evaluate gut lignocellulase activities after no-choice feeding (iii) to determine impacts of feedstock on foraging activities and survival behavior. Sugarcane bagasse, pinewood, cottonwood and corn stovers were saccharified at significantly high level as compared to control diet and rice husk. The gut protein extract from both termite species saccharified all lignocellulose material regardless of feedstock loading. However, R. flavipes showed significantly (p<0.05) high saccharification potential than H. indicola . Consumption of the sugarcane bagasse, pinewood and corn stover was maximum by R. flavipes , whereas, H. indicola exposed cottonwood and sugarcane feedstocks as most palatable food source with 100% survivability. Hypothesis of this study was that feeding on various feedstocks will show variable impacts on enzyme activities, since an adaptive mechanism enables the termites and their endosymbionts for optimized consumption of variable food source. Results supported “diet adaptation” hypothesis by indicating β- glucosidase, exoglucanase and xylanase activities significantly highest for sugarcane bagasse, pinewood and cottonwood as compared to rice husk and control diets in both termite species. These results are important in perspective of physiological changes in termites that lead to gut microbial environments changes and 100% survivability on exclusive sugarcane bagasse, pinewood and cottonwood feedstocks