Microbial community changes in methanogenic granules during the transition from mesophilic to thermophilic conditions
Upflow anaerobic sludge blanket (UASB) reactor is one of the most applied technologies for various high-strength wastewater treatments. The present study analysed the microbial community changes in UASB granules during the transition from mesophilic to thermophilic conditions. Dynamicity of microbial community in granules was analysed using high-throughput sequencing of 16S ribosomal RNA gene amplicons, and the results showed that the temperature strictly determines the diversity of the microbial consortium. It was demonstrated that most of the microbes which were present in the initial mesophilic community were not found in the granules after the transition to thermophilic conditions. More specifically, only members from family Anaerolinaceae managed to tolerate the temperature change and contributed in maintaining the physical integrity of granular structure. On the contrary, new hydrolytic and fermentative bacteria were quickly replacing the old members in the community. A direct result from this abrupt change in the microbial diversity was the accumulation of volatile fatty acids and the concomitant pH drop in the reactor inhibiting the overall anaerobic digestion process. Nevertheless, by maintaining deliberately the pH levels at values higher than 6.5, a methanogen belonging to Methanoculleus genus emerged in the community enhancing the methane production.
KeywordsUASB Temperature Microbial community Granule structure 16S rRNA gene
We thank Hector Garcia and Hector Diaz for technical assistance. X. Zhu acknowledges the financial support provided by the Integrated Water Technology (InWaTech) project, research collaboration between the Technical University of Denmark and the Korean Advanced Institute of Science and Technology (DTU-KAIST, http://www.inwatech.org). This work was supported by the Danish Council for Strategic Research under the project “SYMBIO – Integration of biomass and wind power for biogas enhancement and upgrading via hydrogen assisted anaerobic digestion”, contract 12-132654. Illumina sequencing was performed at the Ramaciotti Centre for Genomics (Sydney, Australia).
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Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- APHA (2005) Standard methods for the examination of water and wastewater. American Public Health AssociationGoogle Scholar
- Liu Y, Balkwill DL, Aldrich HC, Drake GR, Boone DR (1999) Characterization of the anaerobic propionate-degrading syntrophs Smithella propionica gen. nov., sp. nov. and Syntrophobacter wolinii. Int J Syst Evol Microbiol 49:545–556Google Scholar
- Ma K, Liu X, Dong X (2005) Methanobacterium beijingense sp. nov., a novel methanogen isolated from anaerobic digesters. Int J Syst Evol Microbiol 55:325–329Google Scholar
- Martini M, Marcone C, Lee IM, Firrao G (2014) The prokarytoes—Firmicutes and Tenericutes, 4th Editio. Springer, Heidelberg New York Dordrecht LondonGoogle Scholar
- Parks DH, Beiko RG (2010) Identifying biologically relevant differences between metagenomic communities. Bioinformatics 26:715–721Google Scholar
- Rainey FA, Stackebrandt E (1993) Transfer of the type species of the genus Thermobacteroides to the genus Thermoanaerobacter as Thermoanaerobacter acetoethylicus (Ben-Bassat and Zeikus 1981) comb. Nov., description of Coprothermobacter gen. Nov., and Reclassification of Thermobacteroides. Int J Syst Evol Microbiol 43:857–859Google Scholar
- Slobodkin AI, Tourova TP, Kostrikina NA, Lysenko AM, German KE, Bonch-Osmolovskaya EA, Birkeland N-K (2006) Tepidimicrobium ferriphilum gen. nov., sp. nov., a novel moderately thermophilic, Fe (III)-reducing bacterium of the order Clostridiales. Int J Syst Evol Microbiol 56:369–372CrossRefPubMedGoogle Scholar
- Wang H, Fotidis IA, Angelidaki I (2015) Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate-oxidizing bacteria. FEMS Microbiol Ecol 91:11Google Scholar
- Yamada T, Sekiguchi Y, Imachi H, Kamagata Y, Ohashi A, Harada H (2005) Diversity, localization, and physiological properties of filamentous microbes belonging to Chloroflexi subphylum I in mesophilic and thermophilic methanogenic sludge granules. Appl Environ Microbiol 71:7493–7503CrossRefPubMedPubMedCentralGoogle Scholar