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<figure><img src="image_9.png" /></figure>
136. Thauer RK, Kaster AK, Seedorf H, Buckel W, Hedderich R. Methanogenic archaea: ecologically relevant differences in energy conservation. Nat Rev Microbiol. 2008;6:579–91.

137. Tholen A, Brune A. Localization and in situ activities of homoace-
togenic bacteria in the highly compartmentalized hindgut of
soil-feeding higher termites (Cubitermes spp.). Appl Environ Microbiol.
1999;65:4497–505.

138. Thong-On A, Suzuki K, Noda S, Inoue JI, Kajiwara S, Ohkuma M. Isolation and characterization of anaerobic bacteria for symbiotic recycling of uric acid nitrogen in the gut of various termites. Microbes Environ. 2012;27:186–92.

139. Tokuda G, Lo N, Watanabe H, Arakawa G, Matsumoto T, Noda H. Major alteration of the expression site of endogenous cellulases in members of an apical termite lineage. Mol Ecol. 2004;13:3219–28.

140. Tokuda G, Mikaelyan A, Fukui C, Matsuura Y, Watanabe H, Fujishima M, et al. Fiber-associated spirochetes are major agents of hemicellulose degradation in the hindgut of wood-feeding higher termites. Proc Natl Acad Sci U S A. 2018;115:E11996–2004.

141. Treitli SC, Kolisko M, Husník F, Keeling PJ, Hampl V. Revealing the meta-
bolic capacity of *Streblomastix strix* and its bacterial symbionts using
single-cell metagenomics. Proc Natl Acad Sci U S A. 2019;116:19675–84.

142. Uritskiy GV, DiRuggiero J, Taylor J. MetaWRAP - a flexible pipeline for genome-resolved metagenomic data analysis. Microbiome. 2018;6:158.

143. Větrovský T, Baldrian P. The variability of the 16S rRNA gene in bacterial genomes and its consequences for bacterial community analyses. PLoS One. 2013;8:e57923.

144. Vu, V.Q. (2011). ggbiplot: a ggplot2 based biplot. R package version 0.55. Available from: http://github.com/vqv/ggbiplot.

145. Wang Q, Garrity GM, Tiedje JM, Cole JR. Naive Bayesian classifier for rapid assignment of rRNA sequences into the new bacterial taxonomy. Appl Environ Microbiol. 2007;73:5261–7.

146. Wang M, Buček A, Šobotník J, Sillam-Dussès D, Evans TA, Roisin Y, et al. Historical biogeography of the termite clade Rhinotermitinae (Blat-todea: Isoptera). Mol Phylogenet Evol. 2019;132:100–4.

147. Warnecke F, Luginbuhl P, Ivanova N, Ghassemian M, Richardson TH, Stege JT, et al. Metagenomic and functional analysis of hindgut microbiota of a wood-feeding higher termite. Nature. 2007;450:560–5.

148. Watanabe H, Noda H, Tokuda G, Lo N. A cellulase gene of termite origin. Nature. 1998;394:330–1.

149. Watanabe H, Tokuda G. Cellulolytic systems in insects. Annu Rev Ento-mol. 2010;55:609–32.

150. Wu D, Jospin G, Eisen JA. Systematic identification of gene families for use as ‘markers’ for phylogenetic and phylogeny-driven ecological studies of bacteria and archaea and their major subgroups. PLoS One. 2013;8:e77033.

151. Wu, H. (2018). Characterizing xylan-degrading enzymes from a putative xylan utilization system derived from termite gut metagenome. PhD thesis, INSA de Toulouse, France.

152. Yamada A, Inoue T, Noda S, Hongoh Y, Ohkuma M. Evolutionary trend of phylogenetic diversity of nitrogen fixation genes in the gut community of wood-feeding termites. Mol Ecol. 2007;16:3768–77.

153. Yamin M. Cellulose metabolism by the flagellate *Trichonympha* from a termite is independent of endosymbiotic bacteria. Science. 1981;211:58–9.

154. Yan D. Protection of the glutamate pool concentration in enteric bacte-
ria. 2007;104:9475–80.

155. Yin Y, Mao X, Yang J, Chen X, Mao F, Xu Y. dbCAN: a web resource for automated carbohydrate-active enzyme annotation. Nucleic Acids Res. 2012;40:W445–51.

156. Yuki M, Kuwahara H, Shintani M, Izawa K, Sato T, Starns D, et al. Domi-
nant ectosymbiotic bacteria of cellulolytic protists in the termite gut
also have the potential to digest lignocellulose. Environ Microbiol.
2015;17:4942–53.

157. Zhang H, Yohe T, Huang L, Entwistle S, Wu P, Yang Z, et al. dbCAN2: A meta server for automated carbohydrate-active enzyme annotation. Nucleic Acids Res. 2018;46:W95–101.

**Publisher's Note**

Springer Nature remains neutral with regard to jurisdictional claims in pub-
lished maps and institutional affiliations.

Ready to submit your research? Choose BMC and benefit from:

* fast, convenient online submission

* thorough peer review by experienced researchers in your field

* rapid publication on acceptance

* support for research data, including large and complex data types

* gold Open Access which fosters wider collaboration and increased citations

* maximum visibility for your research: over 100M website views per year

At BMC, research is always in progress.

Learn more biomedcentral.com/submissions

<figure><img src="image_10.png" /></figure>