A metabolic model for acetate uptake under anaerobic conditions by glycogen accumulating organisms: Stoichiometry, kinetics, and the effect of pH

Filipe, Carlos D. M.; Daigger, Glen T.; Grady, C. P. Leslie

doi:10.1002/bit.1022

Cited by 194 publications

(247 citation statements)

References 20 publications

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“…The primary fractions of PHA formed through propionate uptake were poly-b-hydroxyvalerate (PHV) and poly-bhydroxy-2-methylvalerate (PH2MV). This differs from GAOs enriched with acetate, which produce primarily poly-b-hydroxybutyrate (PHB) and PHV (Filipe et al, 2001a;Zeng et al, 2003b).…”

Section: Results and Discussion Sbr Operationmentioning

confidence: 99%

“…Metabolic models have been proposed to describe the biochemical transformations occurring in PAOs consuming acetate (Smolders et al, 1994a(Smolders et al, , b, 1995 and propionate (Oehmen et al, 2005b) as the sole carbon source. Similarly, GAO enrichments consuming acetate have also been modelled (Filipe et al, 2001a;Zeng et al, 2002Zeng et al, , 2003b. These metabolic models provide useful tools for optimization of EBPR and for research into the competition between PAOs and GAOs.…”

Section: Introductionmentioning

confidence: 99%

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Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

et al. 2006

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In the microbial competition observed in enhanced biological phosphorus removal (EBPR) systems, an undesirable group of micro-organisms known as glycogen-accumulating organisms (GAOs) compete for carbon in the anaerobic period with the desired polyphosphate-accumulating organisms (PAOs). Some studies have suggested that a propionate carbon source provides PAOs with a competitive advantage over GAOs in EBPR systems; however, the metabolism of GAOs with this carbon source has not been previously investigated. In this study, GAOs were enriched in a laboratory-scale bioreactor with propionate as the sole carbon source, in an effort to better understand their biochemical processes. Based on comprehensive solid-, liquid-and gas-phase chemical analytical data from the bioreactor, a metabolic model was proposed for the metabolism of propionate by GAOs. The model adequately described the anaerobic stoichiometry observed through chemical analysis, and can be a valuable tool for further investigation of the competition between PAOs and GAOs, and for the optimization of the EBPR process. A group of Alphaproteobacteria dominated the biomass (96 % of Bacteria) from this bioreactor, while postfluorescence in situ hybridization (FISH) chemical staining confirmed that these Alphaproteobacteria produced poly-b-hydroxyalkanoates (PHAs) anaerobically and utilized them aerobically, demonstrating that they were putative GAOs. Some of the Alphaproteobacteria were related to Defluvicoccus vanus (16 % of Bacteria), but the specific identity of many could not be determined by FISH. Further investigation into the identity of other GAOs is necessary.

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Section: Results and Discussion Sbr Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

et al. 2006

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“…The enriched cultures of glycogen accumulating organisms were reported to utilize VFA from fermented sugarcane molasses to produce copolymers having 3HB (56-70 mol%), 3HV (13-43 mol%), 3HHx (1-23 mol%), 3H2 MB (0-2 mol%) and 3H2MV (0-2 mol%) which varied with VFA composition [7]. In addition to 3HV, presence of propionate in media also promoted 3H2MB and 3H2MV in the polymer as these could be formed through the combination of acetyl-and propionyl-CoA [60,61]. Lactate is more likely to promote 3HB in a polymer by both pure and mixed cultures [7].…”

Section: Substrate and Feeding Regimementioning

confidence: 99%

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

et al. 2015

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Polyhydroxyalkanoates (PHAs) as an alternative to synthetic plastics have been gaining increasing attention. Being natural in their origin, PHAs are completely biodegradable and eco-friendly. However, consistent efforts to exploit this biopolymer over the last few decades have not been able to pull PHAs out of their nascent stage, inspite of being the favorite of the commercial world. The major limitations are: (1) the high production cost, which is due to the high cost of the feed and (2) poor thermal and mechanical properties of polyhydroxybutyrate (PHB), the most commonly produced PHAs. PHAs have the physicochemical properties which are quite comparable to petroleum based plastics, but PHB being homopolymers are quite brittle, less elastic and have thermal properties which are not suitable for processing them into sturdy products. These properties, including melting point (T m ), glass transition temperature (T g ), elastic modulus, tensile strength, elongation etc. can be improved by varying the monomeric composition and molecular weight. These enhanced characteristics can be achieved by modifications in the types of substrates, feeding strategies, culture conditions and/or genetic manipulations.

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“…PHAs are most typically synthesised in MMCs from volatile fatty acids (VFAs), through well-described metabolic pathways (Filipe et al 2001, Taguchi et al 2005. In the specific case of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), acetic and propionic acids are transported though the cell membrane and converted into acetyl-CoA and propionyl-CoA respectively.…”

Section: 1mentioning

confidence: 99%

“…The metabolic network on which the model is based is summarised in Figure 5 (Filipe et al 2001, Dias et al 2008). Subsequently, PHA precursors are polymerised to form the biopolymer (PHB and PHV), with two units of acetylCoA * forming one 3HB molecule, and one unit of acetyl-CoA * and one of propionyl-CoA * forming one molecule of 3HV.…”

Section: Metabolic Network 5241mentioning

confidence: 99%

Composition of mixed culture PHA biopolymers and implications for downstream processing

Montano-Herrera¹

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Polyhydroxyalkanoates (PHAs) are biopolymers synthesised and accumulated by most bacteria for carbon and energy storage. They have properties and applications comparable to petrochemical thermoplastics. Although PHAs are produced at high yields using pure biological cultures, the use of mixed cultures can significantly reduce the production costs and make use of waste streams to produce environmentally sustainable materials. In order to produce mixed culture PHAs of relevance for broader industry applications it is necessary to develop the ability to tailor polymers with diversified mechanical properties through understanding and controlling the monomer composition and compositional distribution.Diverse and complex PHA polymer structures have been achieved in mixed microbial cultures using time-based feeding strategies. However, PHA monomer composition and compositional distribution in PHA random and blocky copolymers are sensitive to substrate feeding history, making more complex the prediction of final PHA content and composition.In this sense, a better understanding of the changing cell physiologies that develop in response to different feeding strategies and substrates is necessary to design optimised feeding strategies and process control algorithms for PHA production.This thesis presents for the first time a comprehensive flux characterisation of monomer development during mixed culture PHA accumulation concurrent with biomass growth using Metabolic Flux Analysis (MFA). A dynamic trend in active biomass growth and in polymer composition was observed and was consistent over replicate accumulations. Monomer (3-hydroxybutyrate and 3-hydroxyvalerate) incorporation into poly(3-hydroxybutyate-co-3-hydroxyvalerate) copolymers in a pilot scale production system was evaluated based on published models that describe polymer production during PHA accumulation. However, it was found that these existing models could not describe the fluctuations in the proportion of Additionally, thermal degradation of mixed culture PHAs during melt processing was assessed by Near-Infrared (NIR) spectroscopy coupled to Multivariate Data Analysis. It was shown that, with correct pretreatment, a copolymeric product that was much more stable to extrusion processing than commercially available PHA was produced.Overall, this thesis explores both the fundamental and applied aspects of PHA production by mixed microbial cultures with concurrent active biomass growth. The use of computational iii tools to explore and help understand the underlying metabolic processes was explored.Polymer composition seems to follow a very complex regulation processes which can be described through the incorporation of more detailed reactions in current metabolic models.Furthermore, this thesis gives further insight into the fundamental properties of the materials produced and an assessment of their potential for degradation during processing.iv

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A metabolic model for acetate uptake under anaerobic conditions by glycogen accumulating organisms: Stoichiometry, kinetics, and the effect of pH

Cited by 194 publications

References 20 publications

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

Composition of mixed culture PHA biopolymers and implications for downstream processing

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