Academic literature on the topic 'PHB volumetric productivity'

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Journal articles on the topic "PHB volumetric productivity"

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Nikel, Pablo I., Alejandra de Almeida, Evelia C. Melillo, Miguel A. Galvagno, and M. Julia Pettinari. "New Recombinant Escherichia coli Strain Tailored for the Production of Poly(3-Hydroxybutyrate) from Agroindustrial By-Products." Applied and Environmental Microbiology 72, no. 6 (June 2006): 3949–54. http://dx.doi.org/10.1128/aem.00044-06.

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ABSTRACT A recombinant E. coli strain (K24K) was constructed and evaluated for poly(3-hydroxybutyrate) (PHB) production from whey and corn steep liquor as main carbon and nitrogen sources. This strain bears the pha biosynthetic genes from Azotobacter sp. strain FA8 expressed from a T5 promoter under the control of the lactose operator. K24K does not produce the lactose repressor, ensuring constitutive expression of genes involved in lactose transport and utilization. PHB was efficiently produced by the recombinant strain grown aerobically in fed-batch cultures in a laboratory scale bioreactor on a semisynthetic medium supplemented with the agroindustrial by-products. After 24 h, cells accumulated PHB to 72.9% of their cell dry weight, reaching a volumetric productivity of 2.13 g PHB per liter per hour. Physical analysis of PHB recovered from the recombinants showed that its molecular weight was similar to that of PHB produced by Azotobacter sp. strain FA8 and higher than that of the polymer from Cupriavidus necator and that its glass transition temperature was approximately 20�C higher than those of PHBs from the natural producer strains.
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Wang, J., and H. Q. Yu. "Cultivation of polyhydroxybutyrate-rich aerobic granular sludge in a sequencing batch reactor." Water Supply 6, no. 6 (December 1, 2006): 81–87. http://dx.doi.org/10.2166/ws.2006.966.

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In this study a two-step strategy was adopted to cultivate Polyhydroxybutyrate (PHB)-rich aerobic granular sludge in a sequencing batch reactor (SBR) fed with a synthetic wastewater. In the first step both oxygen and ammonia were initially limited, in order to enhance the PHB-storage ability of sludge. In the second step granular sludge was cultivated to get a high PHB volumetric productivity. The PHB content of sludge increased to 43.1±2.0% in the first step. During the sludge granulation, the PHB content was constant at 40±4.6%. With the granulation, the settling ability of the PHB-rich sludge continuously improved, as evidenced by a decreased sludge volume index. The matured PHB-rich granular sludge presented a buff color and regular morphology with elliptical and flat shape.
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Hermann-Krauss, Carmen, Martin Koller, Alexander Muhr, Hubert Fasl, Franz Stelzer, and Gerhart Braunegg. "Archaeal Production of Polyhydroxyalkanoate (PHA) Co- and Terpolyesters from Biodiesel Industry-Derived By-Products." Archaea 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/129268.

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The archaeonHaloferax mediterraneiwas selected for production of PHA co- and terpolyesters using inexpensive crude glycerol phase (CGP) from biodiesel production as carbon source. CGP was assessed by comparison with the application of pure glycerol. Applying pure glycerol, a copolyester with a molar fraction of 3-hydroxybutyrate (3HB) of 0.90 mol/mol and 3-hydroxyvalerate (3HV) of 0.10 mol/mol, was produced at a volumetric productivity of 0.12 g/Lh and an intracellular PHA content of 75.4 wt.-% in the sum of biomass protein plus PHA. Application of CGP resulted in the same polyester composition and volumetric productivity, indicating the feasibility of applying CGP as feedstock. Analysis of molar mass distribution revealed a weight average molar massMwof 150 kDa and polydispersityPiof 2.1 for pure glycerol and 253 kDa and 2.7 for CGP, respectively; melting temperatures ranged between 130 and 140°C in both setups. Supplyingγ-butyrolactone as 4-hydroxybutyrate (4HB) precursor resulted in a poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate-co-4-hydroxybutyrate] (PHBHV4HB) terpolyester containing 3HV (0.12 mol/mol) and 4HB (0.05 mol/mol) in the poly[(R)-3-hydroxybutyrate] (PHB) matrix; in addition, this process runs without sterilization of the bioreactor. The terpolyester displayed reduced melting (melting endotherms at 122 and 137°C) and glass transition temperature (2.5°C), increased molar mass (391 kDa), and a polydispersity similar to the copolyesters.
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Blunt, Warren, David Levin, and Nazim Cicek. "Bioreactor Operating Strategies for Improved Polyhydroxyalkanoate (PHA) Productivity." Polymers 10, no. 11 (October 26, 2018): 1197. http://dx.doi.org/10.3390/polym10111197.

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Microbial polyhydroxyalkanoates (PHAs) are promising biodegradable polymers that may alleviate some of the environmental burden of petroleum-derived polymers. The requirements for carbon substrates and energy for bioreactor operations are major factors contributing to the high production costs and environmental impact of PHAs. Improving the process productivity is an important aspect of cost reduction, which has been attempted using a variety of fed-batch, continuous, and semi-continuous bioreactor systems, with variable results. The purpose of this review is to summarize the bioreactor operations targeting high PHA productivity using pure cultures. The highest volumetric PHA productivity was reported more than 20 years ago for poly(3-hydroxybutryate) (PHB) production from sucrose (5.1 g L−1 h−1). In the time since, similar results have not been achieved on a scale of more than 100 L. More recently, a number fed-batch and semi-continuous (cyclic) bioreactor operation strategies have reported reasonably high productivities (1 g L−1 h−1 to 2 g L−1 h−1) under more realistic conditions for pilot or industrial-scale production, including the utilization of lower-cost waste carbon substrates and atmospheric air as the aeration medium, as well as cultivation under non-sterile conditions. Little development has occurred in the area of fully continuously fed bioreactor systems over the last eight years.
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Blunt, Warren, Christopher Dartiailh, Richard Sparling, Daniel J. Gapes, David B. Levin, and Nazim Cicek. "Development of High Cell Density Cultivation Strategies for Improved Medium Chain Length Polyhydroxyalkanoate Productivity Using Pseudomonas putida LS46." Bioengineering 6, no. 4 (September 26, 2019): 89. http://dx.doi.org/10.3390/bioengineering6040089.

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High cell density (HCD) fed-batch cultures are widely perceived as a requisite for high-productivity polyhydroxyalkanoate (PHA) cultivation processes. In this work, a reactive pulse feed strategy (based on real-time CO2 or dissolved oxygen (DO) measurements as feedback variables) was used to control an oxygen-limited fed-batch process for improved productivity of medium chain length (mcl-) PHAs synthesized by Pseudomonas putida LS46. Despite the onset of oxygen limitation half-way through the process (14 h post inoculation), 28.8 ± 3.9 g L−1 total biomass (with PHA content up to 61 ± 8% cell dry mass) was reliably achieved within 27 h using octanoic acid as the carbon source in a bench-scale (7 L) bioreactor operated under atmospheric conditions. This resulted in a final volumetric productivity of 0.66 ± 0.14 g L−1 h−1. Delivering carbon to the bioreactor as a continuous drip feed process (a proactive feeding strategy compared to pulse feeding) made little difference on the final volumetric productivity of 0.60 ± 0.04 g L−1 h−1. However, the drip feed strategy favored production of non-PHA residual biomass during the growth phase, while pulse feeding favored a higher rate of mcl-PHA synthesis and yield during the storage phase. Overall, it was shown that the inherent O2-limitation brought about by HCD cultures can be used as a simple and effective control strategy for mcl-PHA synthesis from fatty acids. Furthermore, the pulse feed strategy appears to be a relatively easy and reliable method for rapid optimization of fed-batch processes, particularly when using toxic substrates like octanoic acid.
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Ruiz, Carolina, Shane T. Kenny, Ramesh Babu P, Meg Walsh, Tanja Narancic, and Kevin E. O’Connor. "High Cell Density Conversion of Hydrolysed Waste Cooking Oil Fatty Acids Into Medium Chain Length Polyhydroxyalkanoate Using Pseudomonas putida KT2440." Catalysts 9, no. 5 (May 21, 2019): 468. http://dx.doi.org/10.3390/catal9050468.

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Waste cooking oil (WCO) is a major pollutant, primarily managed through incineration. The high cell density bioprocess developed here allows for better use of this valuable resource since it allows the conversion of WCO into biodegradable polymer polyhydroxyalkanoate (PHA). WCO was chemically hydrolysed to give rise to a mixture of fatty acids identical to the fatty acid composition of waste cooking oil. A feed strategy was developed to delay the stationary phase, and therefore achieve higher final biomass and biopolymer (PHA) productivity. In fed batch (pulse feeding) experiments Pseudomonas putida KT2440 achieved a PHA titre of 58 g/l (36.4% of CDW as PHA), a PHA volumetric productivity of 1.93 g/l/h, a cell density of 159.4 g/l, and a biomass yield of 0.76 g/g with hydrolysed waste cooking oil fatty acids (HWCOFA) as the sole substrate. This is up to 33-fold higher PHA productivity compared to previous reports using saponified palm oil. The polymer (PHA) was sticky and amorphous, most likely due to the long chain monomers acting as internal plasticisers. High cell density cultivation is essential for the majority of industrial processes, and this bioprocess represents an excellent basis for the industrial conversion of WCO into PHA.
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Carvalho, João M., Bruno C. Marreiros, and Maria A. M. Reis. "Polyhydroxyalkanoates Production by Mixed Microbial Culture under High Salinity." Sustainability 14, no. 3 (January 25, 2022): 1346. http://dx.doi.org/10.3390/su14031346.

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The fishing industry produces vast amounts of saline organic side streams that require adequate treatment and disposal. The bioconversion of saline resources into value-added products, such as biodegradable polyhydroxyalkanoates (PHAs), has not yet been fully explored. This study investigated PHA production by mixed microbial cultures under 30 gNaCl/L, the highest NaCl concentration reported for the acclimatization of a PHA-accumulating mixed microbial culture (MMC). The operational conditions used during the culture-selection stage resulted in an enriched PHA-accumulating culture dominated by the Rhodobacteraceae family (95.2%) and capable of storing PHAs up to 84.1% wt. (volatile suspended solids (VSS) basis) for the highest organic loading rate (OLR) applied (120 Cmmol/(L.d)). This culture presented a higher preference for the consumption of valeric acid (0.23 ± 0.03 CmolHVal/(CmolX.h)), and the 3HV monomer polymerization (0.33 ± 0.04 CmmolHV/(CmmolX.h) was higher as well. As result, a P(3HB-co-3HV)) with high HV content (63% wt.) was produced in the accumulation tests conducted at higher OLRs and with 30 gNaCl/L. A global volumetric PHA productivity of 0.77 gPHA/(L.h) and a specific PHA productivity of 0.21 gPHA/(gX.h) were achieved. These results suggested the significant potential of the bioconversion of saline resources into value-added products, such as PHAs.
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Oehmen, Adrian, Fátima V. Pinto, Vera Silva, Maria G. E. Albuquerque, and Maria A. M. Reis. "The impact of pH control on the volumetric productivity of mixed culture PHA production from fermented molasses." Engineering in Life Sciences 14, no. 2 (November 22, 2013): 143–52. http://dx.doi.org/10.1002/elsc.201200220.

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Koller, Martin, Denis Vadlja, Gerhart Braunegg, Aid Atlić, and Predrag Horvat. "Formal- and high-structured kinetic process modelling and footprint area analysis of binary imaged cells: Tools to understand and optimize multistage-continuous PHA biosynthesis." EuroBiotech Journal 1, no. 3 (July 20, 2017): 203–11. http://dx.doi.org/10.24190/issn2564-615x/2017/03.01.

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Abstract Competitive polyhydroxyalkanoate (PHAs) production requires progress in microbial strain performance, feedstock selection, downstream processing, and more importantly according to the process design with process kinetics of the microbial growth phase and the phase of product formation. The multistage continuous production in a bioreactor cascade was described for the first time in a continuously operated, flexible five-stage bioreactor cascade that mimics the characteristics involved in the engineering process of tubular plug flow reactors. This process was developed and used for Cupriavidus necator-mediated PHA production at high volumetric and specific PHA productivity (up to 2.31 g/(Lh) and 0.105 g/(gh), respectively). Based on the experimental data, formal kinetic and high structured kinetic models were established, accompanied by footprint area analysis of binary imaged cells. As a result of the study, there has been an enhanced understanding of the long-term continuous PHA production under balanced, transient, and nutrient-deficient conditions that was achieved on both the micro and the macro kinetic level. It can also be concluded that there were novel insights into the complex metabolic occurrences that developed during the multistage- continuous production of PHA as a secondary metabolite. This development was essential in paving the way for further process improvement. At the same time, a new method of specific growth rate and specific production rate based on footprint area analysis was established by using the electron microscope.
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Chen, Si, You-Wei Cui, and Mei-Qi Huang. "Coupling Magnetic Field and Salinity Upshock To Improve Polyhydroxyalkanoate Productivity by Haloferax mediterranei Feeding on Molasses Wastewater." Applied and Environmental Microbiology, June 13, 2022. http://dx.doi.org/10.1128/aem.00305-22.

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The obstacle to replacing petroplastics with PHA is its high production cost. To increase the fermentation economy, a novel strategy of coupling a MF with salinity upshock was applied, which enhanced the PHA volumetric productivity of H. mediterranei in fermenting molasses wastewater.
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Dissertations / Theses on the topic "PHB volumetric productivity"

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MONGILI, BEATRICE. "Biotechnological approches for green-based bioplastic production." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2836776.

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