Polyhydroxyalkanoates: bioplastics with a green agenda

Keshavarz, Tajalli; Roy, Ipsita

doi:10.1016/j.mib.2010.02.006

Cited by 446 publications

(265 citation statements)

References 77 publications

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“…Production of PHB and alginate is closely regulated in A. vinelandii. 10 The results obtained herein may provide valuable hints on the relationships among alginate, PHB, and cyst formation.…”

Section: Resultsmentioning

confidence: 75%

“…8 PHB belongs to the polyhydroxyalkanoate (PHA) family of polyesters, and many bacterial species accumulate PHAs as intracellular granules for energy storage. 10 PHAs are also promising alternatives to plastics because of their biodegradability, biocompatibility, and thermoplasticity. 6,11 Hence, A. vinelandii is considered to be an attractive bacterium for production of 2 industrially useful biopolymers, alginate and PHB, in the absence of nitrogen sources.…”

Section: Introductionmentioning

confidence: 99%

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Production of polyhydroxybutyrate and alginate from glycerol byAzotobacter vinelandiiunder nitrogen-free conditions

et al. 2015

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Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-D-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including g-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source.

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Section: Resultsmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Production of polyhydroxybutyrate and alginate from glycerol byAzotobacter vinelandiiunder nitrogen-free conditions

et al. 2015

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“…Polyhydroxyalkanoates (PHAs) are biodegradable bioplastics that can be produced by bacteria from renewable resources (Kleerebezem and van Loosdrecht, 2007;Keshavarz and Roy, 2010). Since the first discovery of PHA production in Bacillus megaterium by Lemoigne, 1926, over 250 different types of bacteria have been reported as natural PHA producers (Steinbü chel, 1991).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to natural producers, genetically-modified organisms are used for the industrial production of PHA (Slater et al, 1988;Braunegg et al, 1998). However, the use of sterile equipment, defined substrates and downstream processing contribute to the high costs of PHA production, which limits the industrial application of PHA (Keshavarz and Roy, 2010).…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature and cycle length on microbial competition in PHB-producing sequencing batch reactor

et al. 2010

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The impact of temperature and cycle length on microbial competition between polyhydroxybutyrate (PHB)-producing populations enriched in feast-famine sequencing batch reactors (SBRs) was investigated at temperatures of 20 1C and 30 1C, and in a cycle length range of 1-18 h. In this study, the microbial community structure of the PHB-producing enrichments was found to be strongly dependent on temperature, but not on cycle length. Zoogloea and Plasticicumulans acidivorans dominated the SBRs operated at 20 1C and 30 1C, respectively. Both enrichments accumulated PHB more than 75% of cell dry weight. Short-term temperature change experiments revealed that P. acidivorans was more temperature sensitive as compared with Zoogloea. This is particularly true for the PHB degradation, resulting in incomplete PHB degradation in P. acidivorans at 20 1C. Incomplete PHB degradation limited biomass growth and allowed Zoogloea to outcompete P. acidivorans. The PHB content at the end of the feast phase correlated well with the cycle length at a constant solid retention time (SRT). These results suggest that to establish enrichment with the capacity to store a high fraction of PHB, the number of cycles per SRT should be minimized independent of the temperature.

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“…These polymers have garnered considerable biotechnological interest, because they have properties ranging from thermoplastics to elastomers, depending on how the monomer units are substituted, with alkyl substituents ranging from CH 3 to C 9 H 19 (3,4). Additionally, PHAs are biodegradable, making them an environmentally friendly and sustainable alternative to petroleum-based plastics (5,6). Such biologically derived materials are used in specialty markets, such as medical devices; however, they are currently not economically competitive in largescale production with traditional petroleum-based plastics.…”

mentioning

confidence: 99%

Structure of the Catalytic Domain of the Class I Polyhydroxybutyrate Synthase from Cupriavidus necator

Wittenborn¹,

Jost²,

Wei³

et al. 2016

Journal of Biological Chemistry

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Edited by F. Peter GuengerichPolyhydroxybutyrate synthase (PhaC) catalyzes the polymerization of 3-(R)-hydroxybutyryl-coenzyme A as a means of carbon storage in many bacteria. The resulting polymers can be used to make biodegradable materials with properties similar to those of thermoplastics and are an environmentally friendly alternative to traditional petroleum-based plastics. A full biochemical and mechanistic understanding of this process has been hindered in part by a lack of structural information on PhaC. Here we present the first structure of the catalytic domain (residues 201-589) of the class I PhaC from Cupriavidus necator (formerly Ralstonia eutropha) to 1.80 Å resolution. We observe a symmetrical dimeric architecture in which the active site of each monomer is separated from the other by ϳ33 Å across an extensive dimer interface, suggesting a mechanism in which polyhydroxybutyrate biosynthesis occurs at a single active site. The structure additionally highlights key side chain interactions within the active site that play likely roles in facilitating catalysis, leading to the proposal of a modified mechanistic scheme involving two distinct roles for the active site histidine. We also identify putative substrate entrance and product egress routes within the enzyme, which are discussed in the context of previously reported biochemical observations. Our structure lays a foundation for further biochemical and structural characterization of PhaC, which could assist in engineering efforts for the production of eco-friendly materials.

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Polyhydroxyalkanoates: bioplastics with a green agenda

Cited by 446 publications

References 77 publications

Production of polyhydroxybutyrate and alginate from glycerol byAzotobacter vinelandiiunder nitrogen-free conditions

Production of polyhydroxybutyrate and alginate from glycerol byAzotobacter vinelandiiunder nitrogen-free conditions

Effect of temperature and cycle length on microbial competition in PHB-producing sequencing batch reactor

Structure of the Catalytic Domain of the Class I Polyhydroxybutyrate Synthase from Cupriavidus necator

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