Unlocking the Mechanisms of Termite-Mediated Lignin Deconstruction and Degradation in Lignocellulosic Biomass

Scientists from the Department of Biological Systems Engineering, Washington State University (United States) obtained insights as to how termites might modify the lignin structural assembly in softwood tissues. Lignin is one component of plant biomass which gives the structural integrity to the plant; however, lignin also imparts "biomass recalcitrance" against non-extreme pretreatment methods for biofuel production. By looking at how termites deconstruct and degrade lignin in this type of lignocellulosic biomass, a better understanding of the critical mechanisms for plant cell wall degradation could be obtained. This could lead to better strategies for delignification pretreatment in the biofuel ethanol production process.

The scientists compared the lignin structures of raw and termite-digested softwood tissues (in termite feces) using advanced analytical techniques. These techniques include "¹³C crosspolarization magic angle spinning and nuclear magnetic resonance (CP-MAS-NMR) spectroscopy, flash pyrolysis with gas chromatography mass spectrometry (Py-GC/MS), and Py-GC-MS in the presence of tetramethylammonium hydroxide (Py-TMAH)-GC/MS".

The following are some highlights of their study:

(1) the levels of one common component in the lignin structure (the "G unit") was found to increase, while at the same time showing evidence of cellulose degradation,
(2) "dehydroxylation and modification of selective intermonomer side-chain linkages in the lignin in the termite feces" is indicated,
(3) "structural modification in lignin could be associated with the formation of additional condensed interunit linkages". The information obtained may be used in future applications for "mimicking the termite system for biochemical conversion of lignocellulosic biomass to fuels and chemicals".

The full paper is published in the open-access journal, Biotechnology for Biofuels (URL) above.