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Shi, Y., Huang, Z., Han, S., Fan, S., and Yang, H. (2015). Phylogenetic diversity of Archaea in the intestinal tract of termites from different lineages. *J. Basic Microbiol.* 55, 1021–1028.

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Sprenger, W. W., Hackstein, J. H. P., and Keltjens, J. T. (2007). The competitive success of *Methanomicrococcus blatticola*, a dominant methylotrophic methanogen in the cockroach hindgut, is supported by high substrate affinities and favorable thermodynamics. *FEMS Microbiol. Ecol.* 60, 266–275. doi: 10.1111/j.1574-6941.2007.00287.x

Sprenger, W. W., Van Belzen, M. C., Rosenberg, J., Hackstein, J. H. P., and Keltjens, J. T. (2000). Methanomicrococcus blatticola gen. nov., sp. nov., a methanol- and methylamine-reducing methanogen from the hindgut of the cockroach *Periplaneta americana*. *Int. J. Syst. Evol. Microbiol.* 50, 1989–1999. doi: 10.1099/00207713-50-6-1989

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Tholen, A., and Brune, A. (2000). Impact of oxygen on metabolic fluxes and in situ rates of reductive acetogenesis in the hindgut of the wood-feeding termite *Reticulitermes flavipes*. *Environ. Microbiol.* 2, 436–449. doi: 10.1046/j.1462-2920.2000.00127.x

Tholen, A., Pester, M., and Brune, A. (2007). Simultaneous methanogenesis and oxygen reduction by *Methanobrevibacter cuticularis* at low oxygen fluxes. *FEMS Microbiol. Ecol.* 62, 303–312. doi: 10.1111/j.1574-6941.2007.00390.x

Thomas, C. M., Quéméner, E. D., Gribaldo, S., and Borrel, G. (2022). Factors shaping the abundance and diversity of the gut archaeome across the animal kingdom. *Nat. Commun.* 13:3358. doi: 10.1038/s41467-022-31038-4

Thomas, C. M., Taib, N., Gribaldo, S., and Borrel, G. (2021). Comparative genomic analysis of *Methanimicrococcus blatticola* provides insights into host-adaptation in archaea and the evolution of methanogenesis. *ISME Commun.* 1:47. doi: 10.1038/s43705-021-00050-y

Tokura, M., Ohkuma, M., and Kudo, T. (2000). Molecular phylogeny of methanogens associated with flagellated protists in the gut and with the gut epithelium of termites. *FEMS Microbiol. Ecol.* 33, 233–240. doi: 10.1016/S0168-6496(00)00065-9

Tokura, M., Tajima, K., and Ushida, K. (1999). Isolation of *Methanobrevibacter* sp. as a ciliate-associated ruminal methanogen. *J. Gen. Appl. Microbiol.* 45, 43–47. doi: 10.2323/jgam.45.43

Treitli, S., Hanousková, P., Benes, V., Brune, A., Čepička, I., and Hampl, V. (2023). Hydrogenotrophic methanogenesis is the key process in the obligately syntrophic consortium of the anaerobic amoeba *Pelomyxa schiedti*. *ISME J.* 17, 1884–1894. doi: 10.1038/s41396-023-01499-6

van Hoek, A. H. A. M., van Alen, T. A., Sprakel, V. S. I., Leunissen, J. A. M., Brigge, T., Vogels, G. D., et al. (2000). Multiple acquisition of methanogenic archaeal symbionts by anaerobic ciliates. *Mol. Biol. Evol.* 17, 251–258. doi: 10.1093/oxfordjournals.molbev.a026304

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