Background:
Currently, the major barrier in biomass utilization is the lack of effective pretreatment of plant cell wall (PCW) so that the carbohydrates can be subsequently hydrolyzed into sugars to be fermented into fuel or chemical molecules. Termites are highly effective in degrading lignocellulosics thus can be used as model biological systems for studying plant cell wall degradation.
Results:
This study discovered combination of specific structural and composition modification of lignin framework and partial degradation of carbohydrate in softwood with physical chewing in termites C. formosanus, which is critical for efficient cell wall digestion. Comparative studies on the termite-chewed and native (control) softwood tissues at the same size were conducted with the aid of advanced analytical techniques; such as, pyrolysis gas chromatography mass spectrometry (Py-GC/MS), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, along with thermogravimetry (TG/DTG). The results strongly suggested a significant increase in the softwood-cellulose enzymatic digestibility after termite chewing, accompanied with utilization of holocellulosic counterparts and increase in hydrolysable capacity of lignin collectively. In another words, termite chewing process should have combined with specific biological pretreatment on the lignin counterpart in the plant cell wall, resulting in increased enzymatic cellulose digestibility in vitro. For the specific lignin unlocking mechanism at this chewing stage, there were mainly specific bonds cleavage of its network, together with modification and redistribution of its functional groups in the resulting chewed plant tissue for better exposure of the carbohydrate within the plant cell wall. Moreover, cleavage between holocellulosic network and lignin molecule during the chewing process resulted in a much better exposure of the carbohydrate within the plant cell wall.
Conclusion:
Collectively, these data indicated participation of lignin-related enzyme(s) or polypeptide(s) and/or esterase(s), along with involvement of cellulases and hemicellulases in the chewing process of C. formosanus, resulting in a mechanical and enzymatic combined for efficient initial pretreatment on biomass. This process could be mimicked for industrial biomass conversion.Source:
http://www.biotechnologyforbiofuels.com/rss/