characterisation and detection of syntrophic acetate-oxidising bacteria
Biogas production through the syntrophic acetate-oxidising pathway.
Acta Universitatis agriculturae Sueciae, 1652-6880
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.
|Title:||Biogas production through the syntrophic acetate-oxidising pathway|
|Subtitle:||characterisation and detection of syntrophic acetate-oxidising bacteria|
|Series/Journal:||Acta Universitatis agriculturae Sueciae (1652-6880)|
|Year of publishing :||May 2012|
|Number of Pages:||70|
|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|
|Department:||(NL, NJ) > Dept. of Microbiology|
|Deposited By:||Maria Westerholm|
|Deposited On:||28 May 2012 09:36|
|Metadata Last Modified:||02 Dec 2014 10:51|
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