Metagenomic and metatranscriptomic characterization of syntrophic propionate- and butyrate-oxidizing bacterial communities in Qiangyong proglacial lake sediments on the Qinghai-Tibet Plateau

Abstract

Proglacial lake is an emergent source of the second most important greenhouse gas methane as the climate continues to warm, and syntrophic bacteria play a crucial role in the sediment organic matter degradation and methane production. However, our understanding of syntrophic bacteria in the proglacial lake sediments is limited. Here, we combined 16S rRNA gene amplicon sequencing, metagenomics, and metatranscriptomics to explore the diversity, function, and activity of syntrophic propionate- and butyrate-oxidizing bacteria (SPOB and SBOB) in sediments of a glacier-fed proglacial lake on the south Qinghai-Tibet Plateau. We identified a diverse array of putative SPOB and SBOB with pronounced spatial and temporal variations, many of which were central in microbial co-occurrence networks. The most abundant SBOB were Syntrophus, Syntrophorhabdus, and unclassified_Syntrophales, and the dominant SPOB included unclassified_Syntrophobacterales, Smithella, and Syntrophobacter. Lake hydrology, water depth, and associated physicochemical properties shape the spatial patterns of sediment syntrophic bacterial communities. Genome-resolved metagenomics revealed 21 and 4 genus-level novel lineages for SPOB and SBOB, respectively. Transcriptomic evidence highlighted high activity of the uncharacterized genera UBA1429 (Anaerolineae) and E44-bin15 (Dehalococcoidia) in propionate oxidation, and JAPLJM01 (Syntrophia) as a dominant player in butyrate oxidation. This study provides the first insight into syntrophic oxidizers in proglacial lake sediments, advancing our understanding of carbon cycling and methane emission in cryosphere aquatic ecosystems.

Graphical abstract

Keywords

the Qinghai-Tibet Plateau / proglacial lake / syntrophic bacteria / propionate and butyrate / metagenome / metatranscriptome

Highlight

	● Syntrophic bacteria were characterized in the sediment of a proglacial lake.
	● Proglacial lake sediments harbour diverse and novel syntrophic bacteria.
	● Syntrophic bacterial communities exhi-bited a high spatial heterogeneity.
	● Hydrology, water depth and associated physicochemical properties shape the spatial patterns of syntrophic bacterial communities.

References

[1] Aal, G.Z.A., Atekwana, E.A., Slater, L.D., Atekwana, E.A., 2004. Effects of microbial processes on electrolytic and interfacial electrical properties of unconsolidated sediments. Geophysical Research Letters31, L12505.

[2] Atekwana, E.A., Atekwana, E.A., Werkema, D.D., Allen, J.P., Smart, L.A., Duris, J.W., Cassidy, D.P., Sauck, W.A., Rossbach, S., 2004. Evidence for microbial enhanced electrical conductivity in hydrocarbon-contaminated sediments. Geophysical Research Letters31, L23501.

[3] Barberán, A., Bates, S.T., Casamayor, E.O., Fierer, N., 2012. Using network analysis to explore co-occurrence patterns in soil microbial communities. The ISME Journal6, 343–351.

[4] Bastian, M., Heymann, S., Jacomy, M., 2009. Gephi: an open source software for exploring and manipulating networks. In: Proceedings of the Third International AAAI Conference on Weblogs and Social Media. San Jose, California, USA: AAAI361–362.

[5] Bertran, E., Ward, L.M., Johnston, D.T., 2020. Draft genome sequence of Desulfofundulus thermobenzoicus subsp. thermosyntrophicus DSM 14055, a moderately thermophilic sulfate reducer. Microbiology Resource Announcements9, e01416-19.

[6] Bolger, A.M., Lohse, M., Usadel, B., 2014. Trimmomatic: a flexible trimmer for Illumina sequence data. Bioinformatics30, 2114–2120.

[7] Buckel, W., Thauer, R.K., 2018. Flavin-based electron bifurcation, ferredoxin, flavodoxin, and anaerobic respiration with protons (Ech) or NAD⁺ (Rnf) as electron acceptors: a historical review. Frontiers in Microbiology9, 401.

[8] Camacho, C., Coulouris, G., Avagyan, V., Ma, N., Papadopoulos, J., Bealer, K., Madden, T.L., 2009. BLAST+: architecture and applications. BMC Bioinformatics10, 421.

[9] Carrivick, J.L., Tweed, F.S., 2013. Proglacial lakes: character, behaviour and geological importance. Quaternary Science Reviews78, 34–52.

[10] Chauhan, A., Ogram, A., Reddy, K.R., 2004. Syntrophic-methanogenic associations along a nutrient gradient in the Florida Everglades. Applied and Environmental Microbiology70, 3475–3484.

[11] Chaumeil, P.A., Mussig, A.J., Hugenholtz, P., Parks, D.H., 2022. GTDB-Tk v2: memory friendly classification with the genome taxonomy database. Bioinformatics38, 5315–5316.

[12] Csardi, G., Nepusz, T., 2006. The igraph software. Complex Systems1695, 1–9.

[13] Culley, A.I., Thaler, M., Kochtitzky, W., Iqaluk, P., Rapp, J.Z., Rautio, M., Kumagai, M., Copland, L., Vincent, W.F., Girard, C., 2023. The Thores Lake proglacial system: remnant stability in the rapidly changing Canadian High Arctic. Arctic Science9, 720–733.

[14] De Bok, F.A.M., Plugge, C.M., Stams, A.J.M., 2004. Interspecies electron transfer in methanogenic propionate degrading consortia. Water Research38, 1368–1375.

[15] De Bok, F.A.M., Stams, A.J.M., Dijkema, C., Boone, D.R., 2001. Pathway of propionate oxidation by a syntrophic culture of Smithella propionica and Methanospirillum hungatei. Applied and Environmental Microbiology67, 1800–1804.

[16] Dolfing, J., Larter, S.R., Head, I.M., 2008. Thermodynamic constraints on methanogenic crude oil biodegradation. The ISME Journal2, 442–452.

[17] Eddy, S.R., 2011. Accelerated profile HMM searches. PLoS Computational Biology7, e1002195.

[18] Edgar, R.C., 2010. Search and clustering orders of magnitude faster than BLAST. Bioinformatics26, 2460–2461.

[19] Edgar, R.C., 2018. Updating the 97% identity threshold for 16S ribosomal RNA OTUs. Bioinformatics34, 2371–2375.

[20] Emerson, J.B., Varner, R.K., Wik, M., Parks, D.H., Neumann, R.B., Johnson, J.E., Singleton, C.M., Woodcroft, B.J., Tollerson, R., Owusu-Dommey, A., Binder, M., Freitas, N.L., Crill, P.M., Saleska, S.R., Tyson, G.W., Rich, V.I., 2021. Diverse sediment microbiota shape methane emission temperature sensitivity in Arctic lakes. Nature Communications12, 5815.

[21] Fu, L., Song, T.Z., Zhang, W., Zhang, J., Lu, Y.H., 2018. Stimulatory effect of magnetite nanoparticles on a highly enriched butyrate-oxidizing consortium. Frontiers in Microbiology9, 1480.

[22] Gan, Y.L., Qiu, Q.F., Liu, P.F., Rui, J.P., Lu, Y.H., 2012. Syntrophic oxidation of propionate in rice field soil at 15 and 30°C under methanogenic conditions. Applied and Environmental Microbiology78, 4923–4932.

[23] Gao, T.G., Kang, S.C., Yao, T.D., Zhao, Y.L., Shang, X.X., Nie, Y., Chen, R.S., Semiletov, I., Zhang, T.G., Luo, X., Wei, D., Zhang, Y.L., 2024. Carbon dynamics shift in changing cryosphere and hydrosphere of the Third Pole. Earth-Science Reviews250, 104717.

[24] Glissmann, K., Conrad, R., 2000. Fermentation pattern of methanogenic degradation of rice straw in anoxic paddy soil. FEMS Microbiology Ecology31, 117–126.

[25] Gu, Z.Q., Liu, K.S., Pedersen, M.W., Wang, F., Chen, Y.Y., Zeng, C., Liu, Y.Q., 2021. Community assembly processes underlying the temporal dynamics of glacial stream and lake bacterial communities. Science of the Total Environment761, 143178.

[26] Guo, B.X., Liu, Y.Q., Liu, P.F., Cai, R.H., Zheng, Q., Shi, Q., He, C., 2025. Glacial snow and ice contribute differentially to the dissolved organic matter in the runoff of Qiangyong Glacier, Tibetan Plateau. Journal of Hydrology652, 132600.

[27] Han, Y.C., Zhang, C.W., Zhao, Z.M., Peng, Y.Y., Liao, J., Jiang, Q.Y., Liu, Q., Shao, Z.Z., Dong, X.Y., 2023. A comprehensive genomic catalog from global cold seeps. Scientific Data10, 596.

[28] Hao, L.P., Michaelsen, T.Y., Singleton, C.M., Dottorini, G., Kirkegaard, R.H., Albertsen, M., Nielsen, P.H., Dueholm, M.S., 2020. Novel syntrophic bacteria in full-scale anaerobic digesters revealed by genome-centric metatranscriptomics. The ISME Journal14, 906–918.

[29] Hidalgo-Ahumada, C.A.P., Nobu, M.K., Narihiro, T., Tamaki, H., Liu, W.T., Kamagata, Y., Stams, A.J.M., Imachi, H., Sousa, D.Z., 2018. Novel energy conservation strategies and behaviour of Pelotomaculum schinkii driving syntrophic propionate catabolism. Environmental Microbiology20, 4503–4511.

[30] Huang, M.Q., Mu, G.L., Mai, F., Zhou, Y.N., Li, X.D., Yang, Q., Shao, B., Wang, J.Q., Tong, Y.D., 2025. Methane cycling in typical emerging proglacial lakes on the Tibetan Plateau: insights into the metabolic mechanisms mediated by microorganisms. Water Research280, 123533.

[31] Jain, C., Rodriguez-R, L.M., Phillippy, A.M., Konstantinidis, K.T., Aluru, S., 2018. High throughput ANI analysis of 90K prokaryotic genomes reveals clear species boundaries. Nature Communications9, 5114.

[32] Jin, Y.D., Lu, Y.H., 2023. Syntrophic propionate oxidation: one of the rate-limiting steps of organic matter decomposition in anoxic environments. Applied and Environmental Microbiology89, e00384–23.

[33] Kang, D.D., Li, F., Kirton, E., Thomas, A., Egan, R., An, H., Wang, Z., 2019. MetaBAT 2: an adaptive binning algorithm for robust and efficient genome reconstruction from metagenome assemblies. PeerJ7, e7359.

[34] Kaupper, T., Mendes, L.W., Lee, H.J., Mo, Y.L., Poehlein, A., Jia, Z.J., Horn, M.A., Ho, A., 2021. When the going gets tough: emergence of a complex methane-driven interaction network during recovery from desiccation-rewetting. Soil Biology and Biochemistry153, 108109.

[35] Kazantseva, E., Donmez, A., Frolova, M., Pop, M., Kolmogorov, M., 2024. Strainy: phasing and assembly of strain haplotypes from long-read metagenome sequencing. Nature Methods21, 2034–2043.

[36] Kelley, L.A., Mezulis, S., Yates, C.M., Wass, M.N., Sternberg, M.J.E., 2015. The Phyre2 web portal for protein modeling, prediction and analysis. Nature Protocols10, 845–858.

[37] Kleinteich, J., Hanselmann, K., Hildebrand, F., Kappler, A., Zarfl, C., 2022. Glacier melt-down changes habitat characteristics and unique microbial community composition and physiology in alpine lake sediments. FEMS Microbiology Ecology98, fiac075.

[38] Kopylova, E., Noé, L., Touzet, H., 2012. SortMeRNA: fast and accurate filtering of ribosomal RNAs in metatranscriptomic data. Bioinformatics28, 3211–3217.

[39] Krylova, N.I., Janssen, P.H., Conrad, R., 1997. Turnover of propionate in methanogenic paddy soil. FEMS Microbiology Ecology23, 107–117.

[40] Langmead, B., Salzberg, S.L., 2012. Fast gapped-read alignment with Bowtie 2. Nature Methods9, 357–359.

[41] Legg, S., 2021. IPCC, 2021: Climate Change 2021–the Physical Science basis. Interaction49, 44–45.

[42] Letunic, I., Bork, P., 2021. Interactive Tree Of Life (iTOL) v5: an online tool for phylogenetic tree display and annotation. Nucleic Acids Research49, W293–W296.

[43] Li, D.H., Luo, R.B., Liu, C.M., Leung, C.M., Ting, H.F., Sadakane, K., Yamashita, H., Lam, T.W., 2016. MEGAHIT v1.0: a fast and scalable metagenome assembler driven by advanced methodologies and community practices. Methods102, 3–11.

[44] Li, H., Handsaker, B., Wysoker, A., Fennell, T., Ruan, J., Homer, N., Marth, G., Abecasis, G., Durbin, R., 1000 Genome Project Data Processing Subgroup, 2009. The sequence alignment/map format and SAMtools. Bioinformatics25, 2078–2079.

[45] Li, M.Y., Sun, X.J., Li, S.N., Zhang, Q.G., 2020. Advances on inorganic hydrochemistry of glacial meltwater runoff in the Qinghai-Tibet Plateau and its surrounding areas. Journal of Glaciology and Geocryology42, 562–574.

[46] Liu, K.S., Liu, Y.Q., Han, B.P., Xu, B.Q., Zhu, L.P., Ju, J.T., Jiao, N.Z., Xiong, J.B., 2019. Bacterial community changes in a glacial-fed Tibetan lake are correlated with glacial melting. Science of the Total Environment651, 2059–2067.

[47] Liu, K.S., Liu, Y.Q., Jiao, N.Z., Xu, B.Q., Gu, Z.Q., Xing, T.T., Xiong, J.B., 2017a. Bacterial community composition and diversity in Kalakuli, an alpine glacial-fed lake in Muztagh Ata of the westernmost Tibetan Plateau. FEMS Microbiology Ecology93, fix085.

[48] Liu, K.S., Liu, Y.Q., Yan, Q., Guo, X.Z., Wang, W.Q., Zhang, Z.H., Hu, A.Y., Xiao, X., Ji, M.K., Liu, P.F., 2024. Temperature-driven shifts in bacterioplankton biodiversity: implications for cold-preferred species in warming Tibetan proglacial lakes. Water Research265, 122263.

[49] Liu, P.F., Lu, Y.H., 2018. Concerted metabolic shifts give new insights into the syntrophic mechanism between propionate-fermenting Pelotomaculum thermopropionicum and hydrogenotrophic Methanocella conradii. Frontiers in Microbiology9, 1551.

[50] Liu, P.F., Qiu, Q.F., Lu, Y.H., 2011. Syntrophomonadaceae-affiliated species as active butyrate-utilizing syntrophs in paddy field soil. Applied and Environmental Microbiology77, 3884–3887.

[51] Liu, P.F., Yang, Y.X., Lü, Z., Lu, Y.H., 2014. Response of a rice paddy soil methanogen to syntrophic growth as revealed by transcriptional analyses. Applied and Environmental Microbiology80, 4668–4676.

[52] Liu, Y.Q., Vick-Majors, T.J., Priscu, J.C., Yao, T.D., Kang, S.C., Liu, K.S., Cong, Z.Y., Xiong, J.B., Li, Y., 2017b. Biogeography of cryoconite bacterial communities on glaciers of the Tibetan Plateau. FEMS Microbiology Ecology93, fix072.

[53] Liu, Y.Q., Yao, T.D., Gleixner, G., Claus, P., Conrad, R., 2013. Methanogenic pathways, ¹³C isotope fractionation, and archaeal community composition in lake sediments and wetland soils on the Tibetan Plateau. Journal of Geophysical Research: Biogeosciences118, 650–664.

[54] Lu, Y., Zhang, Q., Wang, X.Y., Zhou, X.N., Zhu, J.Y., 2020. Effect of pH on volatile fatty acid production from anaerobic digestion of potato peel waste. Bioresource Technology316, 123851.

[55] Ma, W., Lin, M., Shen, P.H., Chi, H.F., Zhang, W.Z., Zhu, J.Y., Tian, S.Y., Liu, P.F., 2025. Exploring methanogenic archaea and their thermal responses in the glacier-fed stream sediments of Rongbuk River basin, Mt. Everest. FEMS Microbiology Ecology101, fiaf044.

[56] Marsh, G., Chernikhova, D., Thiele, S., Altshuler, I., 2024. Microbial dynamics in rapidly transforming Arctic proglacial landscapes. PLoS Climate3, e0000337.

[57] Martins, P.D., Danczak, R.E., Roux, S., Frank, J., Borton, M.A., Wolfe, R.A., Burris, M.N., Wilkins, M.J., 2018. Viral and metabolic controls on high rates of microbial sulfur and carbon cycling in wetland ecosystems. Microbiome6, 138.

[58] McInerney, M.J., Sieber, J.R., Gunsalus, R.P., 2009. Syntrophy in anaerobic global carbon cycles. Current Opinion in Biotechnology20, 623–632.

[59] McInerney, M.J., Struchtemeyer, C.G., Sieber, J., Mouttaki, H., Stams, A.J.M., Schink, B., Rohlin, L., Gunsalus, R.P., 2008. Physiology, ecology, phylogeny, and genomics of microorganisms capable of syntrophic metabolism. Annals of the New York Academy of Sciences1125, 58–72.

[60] Milner, A.M., Khamis, K., Battin, T.J., Brittain, J.E., Barrand, N.E., Füreder, L., Cauvy-Fraunié, S., Gíslason, G.M., Jacobsen, D., Hannah, D.M., Hodson, A.J., Hood, E., Lencioni, V., Ólafsson, J.S., Robinson, C.T., Tranter, M., Brown, L.E., 2017. Glacier shrinkage driving global changes in downstream systems. Proceedings of the National Academy of Sciences of the United States of America114, 9770–9778.

[61] Moser, K.A., Baron, J.S., Brahney, J., Oleksy, I.A., Saros, J.E., Hundey, E.J., Sadro, S., Kopáček, J., Sommaruga, R., Kainz, M.J., Strecker, A.L., Chandra, S., Walters, D.M., Preston, D.L., Michelutti, N., Lepori, F., Spaulding, S.A., Christianson, K.R., Melack, J.M., Smol, J.P., 2019. Mountain lakes: eyes on global environmental change. Global and Planetary Change178, 77–95.

[62] Mu, C.C., Abbott, B.W., Norris, A.J., Mu, M., Fan, C.Y., Chen, X., Jia, L., Yang, R.M., Zhang, T.J., Wang, K., Peng, X.Q., Wu, Q.B., Guggenberger, G., Wu, X.D., 2020. The status and stability of permafrost carbon on the Tibetan Plateau. Earth-Science Reviews211, 103433.

[63] Müller, N., Worm, P., Schink, B., Stams, A.J.M., Plugge, C.M., 2010. Syntrophic butyrate and propionate oxidation processes: from genomes to reaction mechanisms. Environmental Microbiology Reports2, 489–499.

[64] Müller, V., Chowdhury, N.P., Basen, M., 2018. Electron bifurcation: a long-hidden energy-coupling mechanism. Annual Review of Microbiology72, 331–353.

[65] Nissen, J.N., Johansen, J., Allesøe, R.L., Sønderby, C.K., Armenteros, J.J.A., Grønbech, C.H., Jensen, L.J., Nielsen, H.B., Petersen, T.N., Winther, O., Rasmussen, S., 2021. Improved metagenome binning and assembly using deep variational autoencoders. Nature Biotechnology39, 555–560.

[66] Olm, M.R., Brown, C.T., Brooks, B., Banfield, J.F., 2017. dRep: a tool for fast and accurate genomic comparisons that enables improved genome recovery from metagenomes through de-replication. The ISME Journal11, 2864–2868.

[67] Parks, D.H., Imelfort, M., Skennerton, C.T., Hugenholtz, P., Tyson, G.W., 2015. CheckM: assessing the quality of microbial genomes recovered from isolates, single cells, and metagenomes. Genome Research25, 1043–1055.

[68] Parks, D.H., Rinke, C., Chuvochina, M., Chaumeil, P.A., Woodcroft, B.J., Evans, P.N., Hugenholtz, P., Tyson, G.W., 2017. Recovery of nearly 8,000 metagenome-assembled genomes substantially expands the tree of life. Nature Microbiology2, 1533–1542.

[69] Peng, J.J., Lü, Z., Rui, J.P., Lu, Y.H., 2008. Dynamics of the methanogenic archaeal community during plant residue decomposition in an anoxic rice field soil. Applied and Environmental Microbiology74, 2894–2901.

[70] Peng, X.F., Wilken, S.E., Lankiewicz, T.S., Gilmore, S.P., Brown, J.L., Henske, J.K., Swift, C.L., Salamov, A., Barry, K., Grigoriev, I.V., Theodorou, M.K., Valentine, D.L., O'Malley, M.A., 2021. Genomic and functional analyses of fungal and bacterial consortia that enable lignocellulose breakdown in goat gut microbiomes. Nature Microbiology6, 499–511.

[71] Peter, H., Jeppesen, E., De Meester, L., Sommaruga, R., 2018. Changes in bacterioplankton community structure during early lake ontogeny resulting from the retreat of the Greenland Ice Sheet. The ISME Journal12, 544–555.

[72] Peter, H., Sommaruga, R., 2016. Shifts in diversity and function of lake bacterial communities upon glacier retreat. The ISME Journal10, 1545–1554.

[73] Qin, Q.L., Xie, B.B., Zhang, X.Y., Chen, X.L., Zhou, B.C., Zhou, J.Z., Oren, A., Zhang, Y.Z., 2014. A proposed genus boundary for the prokaryotes based on genomic insights. Journal of Bacteriology196, 2210–2215.

[74] Qiu, Z.G., Yuan, L., Lian, C.A., Lin, B., Chen, J., Mu, R., Qiao, X.J., Zhang, L.Y., Xu, Z., Fan, L., Zhang, Y.Z., Wang, S.Q., Li, J.Y., Cao, H.L., Li, B., Chen, B.W., Song, C., Liu, Y.X., Shi, L.L., Tian, Y.H., Ni, J.R., Zhang, T., Zhou, J.Z., Zhuang, W.Q., Yu, K., 2024. BASALT refines binning from metagenomic data and increases resolution of genome-resolved metagenomic analysis. Nature Communications15, 2179.

[75] Ren, S.T, Menenti, M., Jia, L., Zhang, J., Zhang, J.X., 2019. Glacier mass balance in the Kangri Karpo Mountains by ZY-3 stereo images and SRTM DEMs between 2000 and 2017. In: IGARSS 2019–2019 IEEE International Geoscience and Remote Sensing Symposium. Yokohama, Japan: IEEE4153–4156.

[76] Rui, J.P., Peng, J.J., Lu, Y.H., 2009. Succession of bacterial populations during plant residue decomposition in rice field soil. Applied and Environmental Microbiology75, 4879–4886.

[77] Schink, B., 1997. Energetics of syntrophic cooperation in methanogenic degradation. Microbiology and Molecular Biology Reviews61, 262–280.

[78] Schmidt, O., Hink, L., Horn, M.A., Drake, H.L., 2016. Peat: home to novel syntrophic species that feed acetate- and hydrogen-scavenging methanogens. The ISME Journal10, 1954–1966.

[79] Schut, G.J., Adams, M.W.W., 2009. The iron-hydrogenase of Thermotoga maritima utilizes ferredoxin and NADH synergistically: a new perspective on anaerobic hydrogen production. Journal of Bacteriology191, 4451–4457.

[80] Schwarz, J.I.K., Eckert, W., Conrad, R., 2007. Community structure of Archaea and Bacteria in a profundal lake sediment Lake Kinneret (Israel). Systematic and Applied Microbiology30, 239–254.

[81] Sedano-Núñez, V.T., Boeren, S., Stams, A.J.M., Plugge, C.M., 2018. Comparative proteome analysis of propionate degradation by Syntrophobacter fumaroxidans in pure culture and in coculture with methanogens. Environmental Microbiology20, 1842–1856.

[82] Shaffer, M., Borton, M.A., McGivern, B.B., Zayed, A.A., La Rosa, S.L., Solden, L.M., Liu, P.F., Narrowe, A.B., Rodríguez-Ramos, J., Bolduc, B., Gazitúa, M.C., Daly, R.A., Smith, G.J., Vik, D.R., Pope, P.B., Sullivan, M.B., Roux, S., Wrighton, K., 2020. DRAM for distilling microbial metabolism to automate the curation of microbiome function. Nucleic Acids Research48, 8883–8900.

[83] Sieber, J.R., Le, H.M., McInerney, M.J., 2014. The importance of hydrogen and formate transfer for syntrophic fatty, aromatic and alicyclic metabolism. Environmental Microbiology16, 177–188.

[84] Sieber, J.R., McInerney, M.J., Gunsalus, R.P., 2012. Genomic insights into syntrophy: the paradigm for anaerobic metabolic cooperation. Annual Review of Microbiology66, 429–452.

[85] Sieber, J.R., Sims, D.R., Han, C., Kim, E., Lykidis, A., Lapidus, A.L., McDonnald, E., Rohlin, L., Culley, D.E., Gunsalus, R., McInerney, M.J., 2010. The genome of Syntrophomonas wolfei: new insights into syntrophic metabolism and biohydrogen production. Environmental Microbiology12, 2289–2301.

[86] Singh, A., Schnürer, A., Dolfing, J., Westerholm, M., 2023. Syntrophic entanglements for propionate and acetate oxidation under thermophilic and high-ammonia conditions. The ISME Journal17, 1966–1978.

[87] Sommaruga, R., 2015. When glaciers and ice sheets melt: consequences for planktonic organisms. Journal of Plankton Research37, 509–518.

[88] Stams, A.J.M., Plugge, C.M., 2009. Electron transfer in syntrophic communities of anaerobic bacteria and archaea. Nature Reviews Microbiology7, 568–577.

[89] Stegen, J.C., Fredrickson, J.K., Wilkins, M.J., Konopka, A.E., Nelson, W.C., Arntzen, E.V., Chrisler, W.B., Chu, R.K., Danczak, R.E., Fansler, S.J., Kennedy, D.W., Resch, C.T., Tfaily, M., 2016. Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover. Nature Communications7, 11237.

[90] St. Pierre, K.A., St. Louis, V.L., Schiff, S.L., Lehnherr, I., Dainard, P.G., Gardner, A.S., Aukes, P.J.K., Sharp, M.J., 2019. Proglacial freshwaters are significant and previously unrecognized sinks of atmospheric CO₂. Proceedings of the National Academy of Sciences of the United States of America116, 17690–17695.

[91] Taghavi, S., Izquierdo, J.A., van der Lelie, D., 2013. Complete genome sequence of Clostridium sp. strain DL-VIII, a novel solventogenic Clostridium species isolated from anaerobic sludge. Genome Announcements1, e00605–13.

[92] Tatusova, T., Ciufo, S., Fedorov, B., O'Neill, K., Tolstoy, I., 2014. RefSeq microbial genomes database: new representation and annotation strategy. Nucleic Acids Research42, D553–D559.

[93] Vanderwall, J.W., Muhlfeld, C.C., Tappenbeck, T.H., Giersch, J., Ren, Z., Elser, J.J., 2024. Mountain glaciers influence biogeochemical and ecological characteristics of high-elevation lakes across the northern Rocky Mountains, USA. Limnology and Oceanography69, 37–52.

[94] Visser, M., Worm, P., Muyzer, G., Pereira, I.A.C., Schaap, P.J., Plugge, C.M., Kuever, J., Parshina, S.N., Nazina, T.N., Ivanova, A.E., Bernier-Latmani, R., Goodwin, L.A., Kyrpides, N.C., Woyke, T., Chain, P., Davenport, K.W., Spring, S., Klenk, H.P., Stams, A.J.M., 2013. Genome analysis of Desulfotomaculum kuznetsovii strain 17^T reveals a physiological similarity with Pelotomaculum thermopropionicum strain SI^T. Standards in Genomic Sciences8, 69–87.

[95] Wang, L., Øien, A., 1986. Determination of Kjeldahl nitrogen and exchangeable ammonium in soil by the indophenol method. Acta Agriculturae Scandinavica36, 60–70.

[96] Wang, Q., Garrity, G.M., Tiedje, J.M., Cole, J.R., 2007. Naive Bayesian classifier for rapid assignment of rRNA sequences into the new bacterial taxonomy. Applied and Environmental Microbiology73, 5261–5267.

[97] Wang, X., Guo, X.Y., Yang, C.D., Liu, Q.H., Wei, J.F., Zhang, Y., Liu, S.Y., Zhang, Y.L., Jiang, Z.L., Tang, Z.G., 2020. Glacial lake inventory of high-mountain Asia in 1990 and 2018 derived from Landsat images. Earth System Science Data12, 2169–2182.

[98] Wang, X.Y., Yang, T., Xu, C.Y., Yong, B., Shi, P.F., 2019. Understanding the discharge regime of a glacierized alpine catchment in the Tianshan Mountains using an improved HBV-D hydrological model. Global and Planetary Change172, 211–222.

[99] Westerholm, M., Calusinska, M., Dolfing, J., 2022. Syntrophic propionate-oxidizing bacteria in methanogenic systems. FEMS Microbiology Reviews46, fuab057.

[100] Worm, P., Koehorst, J.J., Visser, M., Sedano-Núñez, V.T., Schaap, P.J., Plugge, C.M., Sousa, D.Z., Stams, A.J.M., 2014. A genomic view on syntrophic versus non-syntrophic lifestyle in anaerobic fatty acid degrading communities. Biochimica et Biophysica Acta (BBA) - Bioenergetics1837, 2004–2016.

[101] Wu, Y.W., Simmons, B.A., Singer, S.W., 2016. MaxBin 2.0: an automated binning algorithm to recover genomes from multiple metagenomic datasets. Bioinformatics32, 605–607.

[102] Yan, F.P., Du, Z.H., Pu, T., Xu, Q., Wang, L., Ma, R.F., Zhang, C., Yu, Z.L., Li, C.L., Kang, S.C., 2023. Isotopic composition and emission characteristics of CO₂ and CH₄ in glacial lakes of the Tibetan Plateau. Environmental Research Letters18, 094025.

[103] Yan, W.F., Wang, D., Wang, Y.B., Wang, C.X., Chen, X., Liu, L., Wang, Y.L., Li, Y.Y., Kamagata, Y., Nobu, M.K., Zhang, T., 2024. Metatranscriptomics-guided genome-scale metabolic reconstruction reveals the carbon flux and trophic interaction in methanogenic communities. Microbiome12, 121.

[104] Yao, T.D., Bolch, T., Chen, D.L., Gao, J., Immerzeel, W., Piao, S.L., Su, F.G., Thompson, L., Wada, Y., Wang, L., Wang, T., Wu, G.J., Xu, B.Q., Yang, W., Zhang, G.Q., Zhao, P., 2022. The imbalance of the Asian water tower. Nature Reviews Earth & Environment3, 618–632.

[105] Yu, T., Luo, Y.F., Tan, X.Y., Zhao, D.H., Bi, X.C., Li, C.J., Zheng, Y.N., Xiang, H., Hu, S.N., 2024. Global marine cold seep metagenomes reveal diversity of taxonomy, metabolic function, and natural products. Genomics, Proteomics & Bioinformatics22, qzad006.

[106] Yue, L.Y., Kong, W.D., Li, C.G., Zhu, G.B., Zhu, L.P., Makhalanyane, T.P., Cowan, D.A., 2021. Dissolved inorganic carbon determines the abundance of microbial primary producers and primary production in Tibetan Plateau lakes. FEMS Microbiology Ecology97, fiaa242.

[107] Zhang, B.G., Liu, J., Sheng, Y.Z., Shi, J.X., Dong, H.L., 2021a. Disentangling microbial syntrophic mechanisms for hexavalent chromium reduction in autotrophic biosystems. Environmental Science & Technology55, 6340–6351.

[108] Zhang, G.Q., Carrivick, J.L., Emmer, A., Shugar, D.H., Veh, G., Wang, X., Labedz, C., Mergili, M., Mölg, N., Huss, M., Allen, S., Sugiyama, S., Lützow, N., 2024a. Characteristics and changes of glacial lakes and outburst floods. Nature Reviews Earth & Environment5, 447–462.

[109] Zhang, J.C., Lu, Y.H., 2016. Conductive Fe₃O₄ nanoparticles accelerate syntrophic methane production from butyrate oxidation in two different lake sediments. Frontiers in Microbiology7, 1316.

[110] Zhang, T.G., Wang, W.C., An, B.S., Gao, T.G., Yao, T.D., 2022. Ice thickness and morphological analysis reveal the future glacial lake distribution and formation probability in the Tibetan Plateau and its surroundings. Global and Planetary Change216, 103923.

[111] Zhang, T.G., Wang, W.C., An, B.S., Wei, L.L., 2023. Enhanced glacial lake activity threatens numerous communities and infrastructure in the Third Pole. Nature Communications14, 8250.

[112] Zhang, Y.L., Gao, T.G., Kang, S.C., Shangguan, D.H., Luo, X., 2021b. Albedo reduction as an important driver for glacier melting in Tibetan Plateau and its surrounding areas. Earth-Science Reviews220, 103735.

[113] Zhang, Z.H., Liu, Y.Q., Liu, K.S., Chen, Y.Y., Guo, X.Z., Ji, M.K., Zhao, W.S., 2024b. Supraglacial and subglacial ecosystems contribute differently towards proglacial ecosystem communities in Kuoqionggangri Glacier, Tibetan Plateau. Communications Earth & Environment5, 636.

[114] Zhao, D.Y., Zhang, P.Y., Liu, Y.Q., Li, Q., Wang, G.J., Chen, R., Li, Y.Y., 2024. Biochar-mediated synergistic promotion of DIET and IHT: Kinetic and thermodynamic insights into propionate two-step syntrophic methanogenesis. Chemical Engineering Journal486, 150310.

[115] Zheng, G.X., Allen, S.K., Bao, A.M., Ballesteros-Cánovas, J.A., Huss, M., Zhang, G.Q., Li, J.L., Yuan, Y., Jiang, L.L., Yu, T., Chen, W.F., Stoffel, M., 2021. Increasing risk of glacial lake outburst floods from future Third Pole deglaciation. Nature Climate Change11, 411–417.

[116] Zhou, Z.C., Tran, P.Q., Breister, A.M., Liu, Y., Kieft, K., Cowley, E.S., Karaoz, U., Anantharaman, K., 2022. METABOLIC: high-throughput profiling of microbial genomes for functional traits, metabolism, biogeochemistry, and community-scale functional networks. Microbiome10, 33.

[117] Ziels, R.M., Nobu, M.K., Sousa, D.Z., 2019. Elucidating syntrophic butyrate-degrading populations in anaerobic digesters using stable-isotope-informed genome-resolved metagenomics. mSystems4, e00159–19.

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