Population Changes of Eubacteria, Sulfate-Reducing Bacteria and Methanogenic Archaea in an Anaerobic Reactor Processing Ethanol Distillery Vinasse

Abstract

The microbiological characterization by molecular techniques (DGGE and quantitative PCR) of Archaea, Bacteria domain and sulfate-reducing bacteria (SRB) from a laboratory scale Up-flow Anaerobic Sludge Blanket (UASB) processing sugar cane vinasse was performed during the operational phase with increasing organic loads. The organic load removal efficiency was between 97% and 75% for volumetric organic loads (VOL) in the range of 0.6 to 15.4 kgCOD.m^-3.d⁻¹ and for higher VOL (until 27.0 kgCOD.m^-3 .d⁻¹) the removal efficiency decreased to 48%. Archaea represented the majority of the estimated population (10⁷ copies of 16S RNA ribosomal gene. mL^-1) followed by bacteria (10⁶ copies of 16S RNA ribosomal gene. mL^-1) and sulfate-reducing bacteria (SRB) (10⁵ copies of dsrB gene. mL^-1). There was a significant difference between the populations of Archaea and SRB with increasing VOL. DGGE profiles show differences among populations with increasing VOL, especially with respect to sulfate-reducing bacteria. The presence of SRB together with a high sulfate removal percentage (97%) of about 15 kgCOD.m^-3d^-1h, indicates the establishment of a sulfidogenic process.

Keywords:
UASB reactor; microbial characterization; Methanogenesis; Sulfidogenesis; DGGE; quantitative PCR