In-situ oxygen profiling and lignin modification in guts of wood-feeding termites

• Published in: Insect science Vol. 17; no. 3; pp. 277 - 290
• Main Authors: Ke, Jing, Sun, Jian-Zhong, Nguyen, Hung D, Singh, Deepak, Lee, Karmen C, Beyenal, Haluk, Chen, Shu-Lin
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Publishing Asia 01-06-2010
• Subjects: Cellulose; Coptotermes formosanus; Digestive tract; Intestine; Isoptera; Lignin; lignin modification; Mass spectroscopy; Microelectrodes; Microenvironments; Midgut; Oxygen; oxygen profile; pretreatment; Reticulitermes flavipes; wood-feeding termites (WFTs); 台湾乳白蚁; 改性木质素; 木质素降解; 氧分析; 裂解气相色谱/质谱法
• ISSN: 1672-9609; 1744-7917
• DOI: 10.1111/j.1744-7917.2010.01336.x

Reports on the capability of wood-feeding termites （WFTs） in degrading wood particles and on the existence of aerobic environment in the localized guts suggest that their high efficiency of cellulose utilization is not only caused by cellulase, but also by biochemical factors that pretreat lignin. We thus extend the hypothesis that for highly efficient accessibility of cellulose, there should be direct evidence of lignin modification before the hindgut. The lignin degradation/modification is facilitated by the oxygenated environment in intestinal microhabitats. To test our hypothesis, we conducted experiments using a dissolved oxygen microelectrode with a tip diameter 〈 10μm to measure oxygen profiles in intestinal microhabitats of both Coptotermes formosanus （Shiraki） and Reticulitermesflavipes （Kollar）. Lignin modification during passage through their three gut segments was also analyzed with pyrolysis gas chromatography/mass spectrometry. The data showed relatively high levels of oxygen in the midgut that could have promoted lignin oxidation. Consistent with the oxygen measurements, lignin modifications were also detected. In support of previously proposed hypotheses, these results demonstrate that lignin disruption, which pretreats wood for cellulose utilization, is initiated in the foregut, and continues in the midgut in both termites.