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| Aerobic activated sludge and anaerobic digestion sludge contain highly complex microbial communities, which play a crucial role in both wastewater treatment and sludge management. Although the responsible microbes have been intensively studied, in communities of high complexity, conventional approaches based on 16S rRNA cannot completely reveal the whole microbial community structure. The metagenomic sequencing was applied to characterize and compare microbial community structure of aerobic activated sludge and anaerobic digestion sludge from a full-scale municipal wastewater treatment plant. Over 3.0 gigabases of metagenomic sequence data were generated with the Illumina HiSeq 2000 platform for each sample. Taxonomic analysis by MG-RAST sever indicated bacteria were dominant in both samples, while archaea with a higher abundance were detected in the anaerobic digestion sludge. The aerobic activated sludge was dominated by Proteobacteria, Bacteroidetes, Nitrospirae, and Actinobacteria, while the most abundant bacterial populations were Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria in anaerobic digestion sludge. Key microorganisms and nitrogen metabolism in aerobic activated sludge and key microorganisms and pathways involved in methanogenesis were further revealed. Ammonia-oxidizing bacteria (AOB) distinctly dominate over ammonia-oxidizing archaea (AOA) in activated sludge. Denitrification, rather than anammox, is the major pathway to complete nitrogen removal. Meanwhile, the dominant proliferation of Methanosaeta and Methanosarcina, together with the functional affiliation of enzymes-encoding genes (Ack, PTA and ACSS) suggested an acetoclastic methanogenesis is the dominant methanogenesis pathway in anaerobic digester. |
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| Keywords:activated sludge; anaerobic digestion sludge; metagenomic sequencing; diversity; bacteria; biological wastewater treatment |
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