title: Microbial community analysis of a biogas-producing completely stirred tank reactor fed continuously with fodder beet silage as mono-substrate.
abstract: The bioconversion of renewable raw material to biogas by anaerobic microbial fermentation processes in completely stirred tank reactors (CSTR) is a valuable alternative resource of energy especially for rural areas. However, knowledge about the microorganisms involved in the degradation of plant biomass is still poor. In this study, a first analysis of the biogas-forming process within a CSTR fed continuously with fodder beet silage as mono-substrate is presented in the context of molecular data on the microbial community composition. As indicated by the conventional process parameters like pH value, content of volatile fatty acids, N:P ratio and the biogas yield, the biogas-forming process within the CSTR occurred with a stable and efficient performance. The average biogas yield based on volatile solids was 0.87m(3)kg(-1) at an organic loading rate of 1.2-2.3kgm(-3)d(-1). This amounts to 94% of the theoretical maximum. In order to identify microorganisms within the CSTR, a 16S rDNA clone library was constructed by PCR amplification applying a prokaryote-specific primer set. One hundred and forty seven clones were obtained and subsequently characterized by amplified rDNA restriction analysis (ARDRA). The sequences of 60 unique ARDRA patterns were estimated in a length of approximately 800-900bp each. Four of them were assigned to the domain Archaea and 56 to the domain Bacteria. Within the domain Archaea, all clones showed a close relationship to methanogenic species. Major bacterial groups represented in the clone library were the class Clostridia of the phylum Firmicutes (22% of all 16S rDNA clones), the class Deltaproteobacteria of the phylum Proteobacteria (24%), the class Bacilli of the phylum Firmicutes (22%) and members of the phylum Bacteroidetes (21%). Within these major groups, the highest biodiversity was found within the class Clostridia (35% of all operational taxonomic units). Members of the phyla Actinobacteria and Spirochaetes were represented only by 5 and 2 clonal sequences, respectively.
authors.affiliation: Leibniz-Institut für Agrartechnik Potsdam-Bornim e.V., Abteilung Bioverfahrenstechnik, Max-Eyth-Allee 100, D-14469 Potsdam-Bornim, Germany. mklocke@atb-potsdam.de
authors.forename: Michael
authors.initials: M
authors.lastname: Klocke
authors.forename: Pia
authors.initials: P
authors.lastname: Mähnert
authors.forename: Kerstin
authors.initials: K
authors.lastname: Mundt
authors.forename: Khadidja
authors.initials: K
authors.lastname: Souidi
authors.forename: Bernd
authors.initials: B
authors.lastname: Linke
mesh_terms: D001105:Archaea / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D027461:Beta vulgaris / Q000378:metabolism; D044822:Biodiversity; D019149:Bioreactors; D003001:Cloning, Molecular; D016172:DNA Fingerprinting / Q000379:methods; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D008697:Methane / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012820:Silage
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D008697:Methane