Fig 1.
Rarefaction curve obtained from MEGAN5 classification.
The curve does not flatten within our sequencing depth, but the increase in the number of leaves in taxonomy is small (ca. 150 leaves with minimal support of 50 per 100,000 reads).
Fig 2.
Methane-yielding community composition based on taxonomic assignments from 454-pyrosequencing reads generated using MEGAN5: (A) total reads; (B) reads assigned to the Bacteria domain, (C) reads assigned to the Archaea domain.
Table 1.
Characteristics of the acidic effluent resulting from molasses fermentation used as the substrate for methanogenesis, and the effluent from the methanogenic process.
Table 2.
Characteristics of biogas generated from the acidic effluent of sugar beet molasses fermentation by the methanogenic microbial community in the UASB bioreactor.
Fig 3.
The expected metabolic pathways used for transformation of the components of the acidic effluent from sugar beet molasses fermentation to methane and carbon dioxide in the UASB bioreactor.
Fig 4.
Scanning electron micrographs of heterogeneous methanogenic sludge from the UASB bioreactor: (a-c) general view; (d-e) granules, (g-i) matrix rich in minerals.
Elemental analysis was performed by the generation of EDS spectra at the indicated points (squares).
Fig 5.
General overview of the functional capabilities of the microbial community in the UASB bioreactor processing acidic effluent from molasses fermentation, drawn with GraPhlAn software (http://huttenhower.sph.harvard.edu/graphlan).
Yellow—pathway modules, light orange—structural complexes, grey—functional sets according to KEGG-based classification. Methane metabolism is highlighted in green. The color scale on the outermost ring represents low relative abundance (black) to high relative abundance (red).