Modeling PHA-producing microbial enrichment cultures—towards a generalized model with predictive power

Tamis, Jelmer; Marang, Leonie; Jiang, Yang; Loosdrecht, M.C.M. van; Kleerebezem, Robbert

doi:10.1016/j.nbt.2013.11.007

Cited by 46 publications

(30 citation statements)

References 59 publications

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“…On the other hand, Johnson et al (2009) set the P/O ratio for all experiments and the m ATP was estimated by fitting. The larger variation in m ATP supports the use of a fixed P/O ratio and subsequent fitting of m ATP (Tamis et al 2014). Significantly though, in these models growth was limited as no nitrogen source was supplied.…”

Section: 1mentioning

confidence: 64%

“…On the other hand, the larger variation in m ATP supports the use of a fixed P/O ratio and subsequent fitting of m ATP (Tamis et al 2014). However, more experiments in fast growing systems are necessary to verify this.…”

Section: Limitations Of Existing Models 535mentioning

confidence: 95%

“…An attempt to formulate a generalised structure based on the experimental data available in literature was recently published (Tamis et al 2014). This model attempts to describe the feast and famine phases with the same kinetics expressions, and prompts the development of further mechanistic expressions.…”

Section: Challenges In Describing and Modelling Microbial Mixed 242mentioning

confidence: 99%

“…Two fundamental model parameters, the maintenance coefficient (m ATP ) and the P/O ratio, have been found to be strongly correlated, making their direct estimation complicated (Tamis et al 2014). …”

Section: Limitations Of Existing Models 535mentioning

confidence: 99%

“…For fast growing systems, it has been stated that the P/O (δ) ratio influences the stoichiometry of the process to a large extent compared with the cell maintenance coefficient (Tamis et al 2014). Therefore the treatment of P/O in terms of a fixed stoichiometry is not necessarily valid for the case of actively growing microorganisms (Zeng et al 1990).…”

Section: Limitations Of Existing Models 535mentioning

confidence: 99%

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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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Section: 1mentioning

confidence: 64%

Section: Limitations Of Existing Models 535mentioning

confidence: 95%

Section: Challenges In Describing and Modelling Microbial Mixed 242mentioning

confidence: 99%

Section: Limitations Of Existing Models 535mentioning

confidence: 99%

Section: Limitations Of Existing Models 535mentioning

confidence: 99%

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Composition of mixed culture PHA biopolymers and implications for downstream processing

Montano-Herrera¹

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Modeling microbial growth and dynamics

Esser

Leveau

Meyer

2015

Appl Microbiol Biotechnol

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Modeling has become an important tool for widening our understanding of microbial growth in the context of applied microbiology and related to such processes as safe food production, wastewater treatment, bioremediation, or microbe-mediated mining. Various modeling techniques, such as primary, secondary and tertiary mathematical models, phenomenological models, mechanistic or kinetic models, reactive transport models, Bayesian network models, artificial neural networks, as well as agent-, individual-, and particle-based models have been applied to model microbial growth and activity in many applied fields. In this mini-review, we summarize the basic concepts of these models using examples and applications from food safety and wastewater treatment systems. We further review recent developments in other applied fields focusing on models that explicitly include spatial relationships. Using these examples, we point out the conceptual similarities across fields of application and encourage the combined use of different modeling techniques in hybrid models as well as their cross-disciplinary exchange. For instance, pattern-oriented modeling has its origin in ecology but may be employed to parameterize microbial growth models when experimental data are scarce. Models could also be used as virtual laboratories to optimize experimental design analogous to the virtual ecologist approach. Future microbial growth models will likely become more complex to benefit from the rich toolbox that is now available to microbial growth modelers.

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Production of a newly discovered PHA family member with an isobutyrate-fed enrichment culture

Vermeer

Bons

Kleerebezem

2022

Appl Microbiol Biotechnol

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Using microbial enrichment cultures for the production of waste-derived polyhydroxyalkanoates (PHAs) is a promising technology to recover secondary resources. Volatile fatty acids (VFAs) form the preferred substrate for PHA production. Isobutyrate is a VFA appearing in multiple waste valorization routes, such as anaerobic fermentation, chain elongation, and microbial electrosynthesis, but has never been assessed individually on its PHA production potential. This research investigates isobutyrate as sole carbon source for a microbial enrichment culture in comparison to its structural isomer butyrate. The results reveal that the enrichment of isobutyrate has a very distinct character regarding microbial community development, PHA productivity, and even PHA composition. Although butyrate is a superior substrate in almost every aspect, this research shows that isobutyrate-rich waste streams have a noteworthy PHA-producing potential. The main finding is that the dominant microorganism, a Comamonas sp., is linked to the production of a unique PHA family member, poly(3-hydroxyisobutyrate) (PHiB), up to 37% of the cell dry weight. This is the first scientific report identifying microbial PHiB production, demonstrating that mixed microbial communities can be a powerful tool for discovery of new metabolic pathways and new types of polymers. Key points • PHiB production is a successful storage strategy in an isobutyrate-fed SBR • Isomers isobutyrate and butyrate reveal a very distinct PHA production behavior • Enrichments can be a tool for discovery of new metabolic pathways and polymers Graphical abstract

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Modeling PHA-producing microbial enrichment cultures—towards a generalized model with predictive power

Cited by 46 publications

References 59 publications

Composition of mixed culture PHA biopolymers and implications for downstream processing

Composition of mixed culture PHA biopolymers and implications for downstream processing

Modeling microbial growth and dynamics

Production of a newly discovered PHA family member with an isobutyrate-fed enrichment culture

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