Lignin Unlocking Process Led by Termites for Efficient Carbohydrate Utilization

Wood-feeding termites are highly effective in deconstruction of wood cell wall structure for efficient utilization of cellulose and hemicelluloses. One of the key factors for its effectual cell wall disintegration is the lignin structure modification for de-protection. In this study, we provide evidence that termites disrupt biomass lignin and abundant aromatic biopolymer significantly, and that their oxidation activities on lignin are associated with oxidative enzymes/peptides in the gut system. Recent results obtained from our laboratory, indicated significant lignin modifications to various lignin structures at different level, as well as the relative catalyst factors, before the hindgut; together with altered chemical environments, such as concentrations of oxygen, hydrogen peroxide, redox potential, and pH value, in termite gut favorable for lignin degradation. Furthermore, the effect of termite-induced lignin modification on enzymatic cellulose hydrolysis was also evaluated. Our advanced analytical techniques allowed us obtain details in gut microenvironment, specific chemical bonding cleavage, functional group change, as well as lignin spatial re-arrangement, by the termite digestive system. Such critical structural modifications on lignin are also proved to play important role in the release of carbohydrate. Overall, these results provide insight into lignin unlocking mechanisms for understanding plant cell wall deconstruction towards development of new enzymatic pretreatment processes for biochemical conversion of lignocellulosic biomass to fuels and chemicals.