Novel nitrifiers and comammox in a full-scale hybrid biofilm and activated sludge reactor revealed by metagenomic approach.
Biofilms are widely used in wastewater treatment for their particular enhancement of nitrogen removal and other significant advantages. In this study, the diversity and potential functions of nitrogen removal bacteria in suspended activated sludge (AS) and biofilm of a full-scale hybrid reactor were uncovered by metagenomes (∼34 Gb), coupled with PCR-based 454 reads (>33 K reads). The results indicated that the diversity and abundance of nitrifiers and denitrifiers in biofilm did not surpass that in AS, while more nitrification and denitrification genes were indeed found in biofilm than AS, suggesting that the increased nitrogen removal ability by applying biofilm might be attributed to the enhancement of removal efficiency, rather than the biomass accumulation of nitrogen removal bacteria. The gene annotation and phylogenetic analysis results revealed that AS and biofilm samples consisted of 6.0 % and 9.4 % of novel functional genes for nitrogen removal and 18 % and 30 % of new Nitrospira species for nitrite-oxidizing bacteria, respectively. Moreover, the identification of Nitrospira-like amoA genes provided metagenomic evidence for the presence of complete ammonia oxidizer (comammox) with the functional potential to perform the complete oxidation of ammonia to nitrate. These findings have significant implications in expanding our knowledge of the biological nitrogen transformations in wastewater treatment.
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.|Environmental Biotechnology Laboratory, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Pok Fu Lam, Hong Kong.|College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China.
Yuanqing
Y
Chao
Environmental Biotechnology Laboratory, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Pok Fu Lam, Hong Kong.|Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China.
Yanping
Y
Mao
Environmental Biotechnology Laboratory, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Pok Fu Lam, Hong Kong.
Ke
K
Yu
Environmental Biotechnology Laboratory, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Pok Fu Lam, Hong Kong. zhangt@hku.hk.
Tong
T
Zhang
D000641:Ammonia / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D019149:Bioreactors / Q000382:microbiology*; D058448:Biota; D058440:Denitrification; D059014:High-Throughput Nucleotide Sequencing; D056186:Metagenomics; D058465:Nitrification; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012722:Sewage / Q000382:microbiology*; D062065:Wastewater; D018508:Water Purification
D000641:Ammonia; D009584:Nitrogen; D012722:Sewage; D062065:Wastewater
Activated sludge; Biofilm; Comammox; Metagenomics; Nitrogen cycle