ABSTRACT
Microbial properties of a methanogenic granular phenol-degrading sludge were characterized using the 16S rRNA/DNA-based techniques, including polymerase chain reaction (PCR) amplification, cloning, DNA sequencing, and fluorescence in situ hybridization (FISH). The sludge was sampled from an upflow anaerobic sludge blanket reactor, which removed 98% of phenol (up to 1260 mg/l) in wastewater at 26 degrees C with 12 hours of hydraulic retention. Based on DNA analysis, the Eubacteria in the sludge was composed of 13 operational taxonomy units (OTUs). Two OTUs, one resembling Clostridium and the other remotely resembling Desulfotomaculum, were likely responsible for the conversion of phenol to benzoate, which was further degraded by five Syntrophus-resembling OTUs to acetate and H2/CO2; methanogens lastly converted acetate and H2/CO2 into methane. The role of six remaining OTUs remains unclear. Overall, the sludge was composed of 26 +/- 6% Eubacteria and 74 +/- 9% methanogens, of which 54 +/- 6% were acetotrophic Methanosaetaceae, 14 +/- 3% and 3 +/- 2% were hydrogenotrophic Methanomicrobiales and Methanobacteriaceae, respectively.
Subject(s)
Bacteria, Anaerobic/isolation & purification , Bacteria/isolation & purification , Euryarchaeota/isolation & purification , Phenol/metabolism , Sewage/microbiology , Bacteria/classification , Bacteria/genetics , Bacteria/metabolism , Bacteria, Anaerobic/classification , Bacteria, Anaerobic/genetics , Bacteria, Anaerobic/metabolism , Base Sequence , Biodegradation, Environmental , Bioreactors , DNA, Archaeal/analysis , DNA, Bacterial/analysis , Euryarchaeota/classification , Euryarchaeota/genetics , Euryarchaeota/metabolism , In Situ Hybridization, Fluorescence , Methane/metabolism , RNA, Ribosomal, 16S/analysis , Sequence Analysis, DNAABSTRACT
Treating a synthetic wastewater containing phenol as the sole substrate at 26 degrees C, an upflow anaerobic sludge blanket reactor was able to remove over 98% of phenol up to 1,260 mg/l in wastewater with 12 h of hydraulic retention time, corresponding to 6.0 g-COD/(l x day). Results showed that benzoate was the key intermediate of phenol degradation. Conversion of benzoate to methane was suppressed by the presence of phenol. Based on DNA cloning analysis, the sludge was composed of five groups of microorganisms. Desulfotomaculum and Clostridium were likely responsible for the conversion of phenol to benzoate, which was further degraded by Syntrophus to acetate and H2/CO2. Methanogens lastly converted acetate and H2/CO2 to methane. The role of epsilon-Proteobacteria was, however, unclear.
