Integrated Omic Analyses Provide Evidence that a " Candidatus Accumulibacter phosphatis" Strain Performs Denitrification under Microaerobic Conditions

The ability of " Accumulibacter phosphatis" to grow and remove phosphorus from wastewater under cycling anaerobic and aerobic conditions has also been investigated as a metabolism that could lead to simultaneous removal of nitrogen and phosphorus by a single organism. However, although pho...

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Bibliographic Details
Published in:mSystems 2019-01, Vol.4 (1)
Main Authors: Camejo, Pamela Y, Oyserman, Ben O, McMahon, Katherine D, Noguera, Daniel R
Format: Article
Language:English
Subjects:
Abundance
Accumulibacter
Aeration
Aerobic conditions
Ammonia
Applied and Environmental Science
BASIC BIOLOGICAL SCIENCES
Candidatus Accumulibacter phosphatis
Denitrification
Experimental research
Gene expression
Gene regulation
Genomes
Genomics
Kinases
Metabolism
metagenomics
Microbiology
Nitrate reduction
Nitrates
Nitrogen removal
Nutrient removal
Oxygen
Phosphorus
Population
Research Article
Respiration
RNA sequencing
Studies
Transcription
transcriptional regulation
Wastewater treatment
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Summary:The ability of " Accumulibacter phosphatis" to grow and remove phosphorus from wastewater under cycling anaerobic and aerobic conditions has also been investigated as a metabolism that could lead to simultaneous removal of nitrogen and phosphorus by a single organism. However, although phosphorus removal under cyclic anaerobic and anoxic conditions has been demonstrated, clarifying the role of " . Accumulibacter phosphatis" in this process has been challenging, since (i) experimental research describes contradictory findings, (ii) none of the published " . Accumulibacter phosphatis" genomes show the existence of a complete respiratory pathway for denitrification, and (iii) some genomes lacking a complete respiratory pathway have genes for assimilatory nitrate reduction. In this study, we used an integrated omics analysis to elucidate the physiology of a " . Accumulibacter phosphatis" strain enriched in a reactor operated under cyclic anaerobic and microaerobic conditions. The reactor's performance suggested the ability of the enriched " . Accumulibacter phosphatis" strain (clade IC) to simultaneously use oxygen and nitrate as electron acceptors under microaerobic conditions. A draft genome of this organism was assembled from metagenomic reads (" . Accumulibacter phosphatis" UW-LDO-IC) and used as a reference to examine transcript abundance throughout one reactor cycle. The genome of UW-LDO-IC revealed the presence of a full pathway for respiratory denitrification. The observed transcript abundance patterns showed evidence of coregulation of the denitrifying genes along with a cytochrome, which has been characterized as having high affinity for oxygen. Furthermore, we identified an FNR-like binding motif upstream of the coregulated genes, suggesting transcription-level regulation of both denitrifying and respiratory pathways in UW-LDO-IC. Taking the results together, the omics analysis provides strong evidence that " . Accumulibacter phosphatis" UW-LDO-IC uses oxygen and nitrate simultaneously as electron acceptors under microaerobic conditions. " Accumulibacter phosphatis" is widely found in full-scale wastewater treatment plants, where it has been identified as the key organism for biological removal of phosphorus. Since aeration can account for 50% of the energy use during wastewater treatment, microaerobic conditions for wastewater treatment have emerged as a cost-effective alternative to conventional biological nutrient removal processes. Our report pr
ISSN:2379-5077
2379-5077
DOI:10.1128/mSystems.00193-18