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Grantee Research Project Results

Grantee Research Project Results

Enzymes Involved in Biological Phosphorus Removal: Polyphosphate Kinase from Sludge

EPA Grant Number: U915770
Title: Enzymes Involved in Biological Phosphorus Removal: Polyphosphate Kinase from Sludge
Investigators: McMahon, Katherine D.
Institution: University of California - Berkeley
EPA Project Officer: Jones, Brandon
Project Period: August 1, 2000 through August 1, 2003
Project Amount: $66,658
RFA: STAR Graduate Fellowships (2000)
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Civil/Environmental Engineering



The overall goal of this research project is to generate a more thorough understanding of the microbial ecology of enhanced biological phosphorus removal (EBPR). This project will address three important questions: (1) What kinds of microorganisms are present in EBPR systems? (2) How does expression of polyphosphate kinase, a gene putatively involved in EBPR, vary as biomass is exposed to alternating anaerobic and aerobic conditions? and (3) How are population dynamics and the expression of this metabolic gene related to process performance?


The community structure and metabolic function of activated sludge carrying out EBPR will be investigated. Several laboratory-scale sequencing batch reactors will operate at a range of influent COD/P ratios to obtain sludges with a range of non-soluble contents. Molecular microbiological techniques based on the ribosomal RNA (rRNA) gene will be used to characterize the community structure and population dynamics of these sludges. Polymerase chain reaction (PCR)-based clone libraries of rRNA genes will be constructed. Fluorescent in situ hybridization (FISH) will quantitatively confirm the distribution of the organisms containing the rRNA sequences found in the libraries. Fragments of genes coding for polyphosphate kinase (PPK), thought to be responsible for polyphosphate accumulation, will be retrieved from one of the sludges using PCR.

Expected Results:

The characterization of the enzymes from uncultivated microorganisms found in EBPR systems will aid in understanding the biochemistry responsible for phosphorus removal. A more complete mechanistic model for EBPR will be developed to encourage more rational design and operation of nutrient removal systems.

Supplemental Keywords:

activated sludge, polyphosphate kinase, PPK, enhanced biological phosphorus removal, EBPR, Rhodocyclus tenuis, nutrient removal, molecular methods, microbial population dynamics, microbial ecology., RFA, Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Ecology, Aquatic Ecosystems & Estuarine Research, Genetics, Wastewater, Aquatic Ecosystem, Microbiology, Civil/Environmental Engineering, Biochemistry, Bioremediation, Molecular Biology/Genetics, Engineering, Chemistry, & Physics, activated sludge, enzymes, enhanced biological phosphorus removal, microbes, biomass, phosphorus, community dynamics, metabolic pathways, sludge

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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