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Anaerobic metabolism of propionate by polyphosphate‐accumulating organisms in enhanced biological phosphorus removal systems
Author(s) -
Oehmen Adrian,
Zeng Raymond J.,
Yuan Zhiguo,
Keller Jürg
Publication year - 2005
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20480
Subject(s) - propionate , enhanced biological phosphorus removal , chemistry , anaerobic exercise , population , biochemistry , metabolism , substrate (aquarium) , enrichment culture , bacteria , activated sludge , biology , sewage treatment , ecology , environmental engineering , physiology , demography , sociology , engineering , genetics
Propionate, a carbon substrate abundant in many prefermenters, has been shown in several previous studies to be a more favorable substrate than acetate for enhanced biological phosphorus removal (EBPR). The anaerobic metabolism of propionate by polyphosphate accumulating organisms (PAOs) is studied in this paper. A metabolic model is proposed to characterize the anaerobic biochemical transformations of propionate uptake by PAOs. The model is demonstrated to predict very well the experimental data from a PAO culture enriched in a laboratory‐scale reactor with propionate as the sole carbon source. Quantitative fluorescence in‐situ hybridization (FISH) analysis shows that Candidatus Accumulibacter phosphatis , the only identified PAO to date, constitute 63% of the bacterial population in this culture. Unlike the anaerobic metabolism of acetate by PAOs, which induces mainly poly‐β‐hydroxybutyrate (PHB) production, the major fractions of poly‐β‐hydroxyalkanoate (PHA) produced with propionate as the carbon source are poly‐β‐hydroxyvalerate (PHV) and poly‐β‐hydroxy‐2‐methylvalerate (PH2MV). PHA formation correlates very well with a selective (or nonrandom) condensation of acetyl‐CoA and propionyl‐CoA molecules. The maximum specific propionate uptake rate by PAOs found in this study is 0.18 C‐mol/C‐mol‐biomass · h, which is very similar to the maximum specific acetate uptake rate reported in literature. The energy required for transporting 1 carbon‐mole of propionate across the PAO cell membrane is also determined to be similar to the transportation of 1 carbon‐mole of acetate. Furthermore, the experimental results suggest that PAOs possess a similar preference toward acetate and propionate uptake on a carbon‐mole basis. © 2005 Wiley Periodicals, Inc.