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Biogas production through the syntrophic acetate-oxidising pathway

characterisation and detection of syntrophic acetate-oxidising bacteria

Westerholm, Maria (2012). Biogas production through the syntrophic acetate-oxidising pathway. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2012:45
ISBN 978-91-576-7681-8
[Doctoral thesis]

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Biogas produced from wastes, residues and energy crops has promising potential to reduce greenhouse gas emissions and to secure future energy supply. Methane is the energy-rich component of biogas, and is formed as the end product during degradation of organic material without oxygen (anaerobic). Acetate is an important intermediate in anaerobic degradation and can be converted to methane through two pathways: aceticlastic methanogenesis and syntrophic acetate oxidation (SAO). SAO is a two-step reaction, consisting of acetate oxidation to hydrogen and carbon dioxide by syntrophic acetate-oxidising bacteria (SAOB), followed by conversion of these products to methane by hydrogenotrophic methanogens. Ammonia and acetate concentration, hydraulic retention time, temperature and methanogenic population structure are operational parameters considered to influence the acetate conversion pathway.

This thesis sought to increase understanding of SAO by examining syntrophic acetate oxidisers in pure culture, co-culture and methanogenic reactors. Two novel species of SAOB, Syntrophaceticus schinkii and Tepidanaerobacter acetatoxydans, were isolated and their phenotypic and phylogenetic traits were characterised. Quantitative molecular approaches were developed and applied to determine structural dynamics in the methane-producing population in a mesophilic biogas reactor during an ammonia-induced shift from aceticlastic to syntrophic acetate degradation. The abundance of SAOB increased, with a simultaneous decrease in aceticlastic methanogens. The majority of known SAOB are considered acetogens, and gradually increased ammonia concentration was shown to cause distinct shifts in the putative acetogenic population structure in mesophilic biogas reactors. However, the acetogenic bacterial abundance remained relatively stable. Bioaugmentation of syntrophic acetate-oxidising cultures did not improve process performance or support establishment of SAO as the dominant acetate degradation pathway.

In conclusion, SAOB are enduring and important components
of the methane-producing community in mesophilic biogas reactors with high prevailing ammonia concentrations.

Authors/Creators:Westerholm, Maria
Title:Biogas production through the syntrophic acetate-oxidising pathway
Subtitle:characterisation and detection of syntrophic acetate-oxidising bacteria
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :May 2012
Number of Pages:70
I.Westerholm, M., Roos, S. & Schnürer, A. (2010). Syntrophaceticus schinkii gen. nov., sp. nov., an anaerobic, syntrophic acetate-oxidising bacterium isolated from a mesophilic anaerobic filter. FEMS Microbiology Letters 309, 100-104.
II.Westerholm, M., Roos, S. & Schnürer, A. (2011). Tepidanaerobacter acetatoxydans sp. nov., an anaerobic, syntrophic acetate-oxidising bacterium isolated from two ammonium-enriched mesophilic methanogenic processes. Systematic and Applied Microbiology 34, 260-266.
III.Westerholm, M., Dolfing, J., Sherry, A., Gray, N.D., Head I.M. & Schnürer, A. (2011). Quantification of syntrophic acetate-oxidising microbial communities in biogas processes. Environmental Microbiology Reports 3, 500-505.
IV.Westerholm, M., Müller, B., Arthurson, V. & Schnürer, A. (2011) Changes in the acetogenic population in a mesophilic anaerobic digester in response to increasing ammonia concentration. Microbes and Environments 26, 347-353.
V.Westerholm, M., Levén, L. & Schnürer, A. Bioaugmentation of syntrophic acetate-oxidising culture in biogas reactors exposed to increasing levels of ammonia (manuscript).
Place of Publication:Uppsala
Publisher:Dept. of Microbiology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7681-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X30 Life sciences
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Biochemistry and Molecular Biology
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Cell Biology
Agrovoc terms:bacteria, mesophile microorganisms, acetates, oxidation, ammonia, biogas
Keywords:syntrophic acetate oxidation, Syntrophaceticus schinkii, Tepidanaerobacter acetatoxydans, microbial population structure, biogas production, ammonia
Permanent URL:
ID Code:8900
Department:(NL, NJ) > Dept. of Microbiology (until 161231)
Deposited By: Maria Westerholm
Deposited On:28 May 2012 09:36
Metadata Last Modified:02 Dec 2014 10:51

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