Chemical, enzymatic and microbial degradation of bacterial and synthetic poly-β-hydroxyalkanoates

Marchessault, R. H.; Monasterios, C.J.; Jesudason, J. J.; Ramsay, Bruce A.; Saracovan, Ilie; Ramsay, J. O.; Saito, Terumi

doi:10.1016/0141-3910(94)90136-8

Cited by 20 publications

(8 citation statements)

References 12 publications

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“…The conclusion that a major part of the nascent granules must be in a highly mobile state was inescapable. This experiment was repeated in our laboratory [18] on isolated suspensions of nascent PHB granules with the same results. Thus, only after water removal does PHB convert, irreversibly, to the crystalline state corresponding to the well-known orthorhombic unit cell with left-handed 21 molecular symmetry [19].…”

Section: Introductionmentioning

confidence: 77%

Topotactic crystallization of isolated poly(β-hydroxybutyrate) granules from Alcaligenes eutrophus

Lauzier¹

1992

FEMS Microbiology Letters

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SUMMARYTransmission electron microscopy (TEM), differential scanning calorimetry (DSC), wide-angle X-ray powder diffractometry (WAXD) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the crystallization behavior of PHB granules from Alcaligenes eutrophus isolated by enzymatic purification. TEM examination of freeze dried granules after mortar and pestle grinding at liquid nitrogen temperature revealed that the dry granules have a non-crystalline core/crystalline shell morphology. TEM micrographs of sections of PHB granules showed that upon annealing, the non-crystalline molecules in the core transform into stacks of lamellar crystals with a thickness of ~ 100 ,~. The FTIR results revealed the presence of bound water in a sample of freeze dried granules and WAXD of the same sample showed an increase in crystallinity after removal of this water by vacuum drying. The WAXD diffractograms showed an Correspondence to: R.H. increase in crystallinity of PHB granules when going from the in vivo to the dry state. In spite of the possibility of deforming them at very low temperatures (liquid nitrogen temperature) the glass transition temperature (Tg) of nascent PHB granules, as revealed by the DSC thermograms, was in the range -0.5-4°C. These results suggest that water is responsible for keeping the core of nascent PHB granules in a non-crystalline state. A model for biosynthesis where emerging PHB chains in an extended conformation are simultaneously hydrogen bonded to water molecules is proposed.

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Section: Introductionmentioning

confidence: 77%

Topotactic crystallization of isolated poly(β-hydroxybutyrate) granules from Alcaligenes eutrophus

Lauzier¹

1992

FEMS Microbiology Letters

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“…granule suspension, solvent or melt cast films, single crystals), crystallinity and crystal size, morphology and temperature [28,36,37].…”

Section: Introductionmentioning

confidence: 99%

Microbial Degradation of Poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate) in Soil

Wen

2011

J Polym Environ

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The microbial degradation of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) copolymers with different 4HB molar fraction were investigated in soil for 60 days. In the degradation process, changes in weight loss and molecular weight were periodically measured to determine the biodegradability; the surface morphology also was observed using scanning electron microscopy and polarizing optical microscopy. The results showed that the rate of degradation of P3/4HB depends strongly on its crystallinity and surface morphology. Enzymatic degradation, which proceeded via surface erosion mechanisms, was observed mainly during the degradation period in soil. The amorphous interspherulitic regions and crystal center were prone to degrade.

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“…Ex situ studies are nevertheless useful as a means to assess biological degradation such as the analysis of carbon dioxide evolved and determination of PHA-degrading microorganisms and extracellular depolymerases (4,5). The rate of degradation is influenced by a number of factors which include the properties of the plastic material such as crystallinity, tacticity, morphology, and composition (6), as well as the physical and chemical properties of the environment and the microbial population in it (4). Methods used to determine PHA degradation include visual observation of the material, changes in gross weight, molecular weight and tensile strength, quantitative determination of microbial growth when PHA is used as carbon source, and determination of microbial activities such as oxygen consumption or carbon dioxide production (7).…”

Section: Introductionmentioning

confidence: 99%

Degradation of medium-chain-length polyhydroxyalkanoates in tropical forest and mangrove soils

Lim

Gan

Tan

2005

Appl Biochem Biotechnol

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Bacterial polyhydroxyalkanoates (PHAs) are perceived to be a suitable alternative to petrochemical plastics because they have similar material properties, are environmentally degradable, and are produced from renewable resources. In this study, the in situ degradation of medium-chain-length PHA (PHAMCL) films in tropical forest and mangrove soils was assessed. The PHAMCL was produced by Pseudomonas putida PGA1 using saponified palm kernel oil (SPKO) as the carbon source. After 112 d of burial, there was 16.7% reduction in gross weight of the films buried in acidic forest soil (FS), 3.0% in the ones buried in alkaline forest soil by the side of a stream (FSst) and 4.5% in those buried in mangrove soil (MS). There was a slight decrease in molecular weight for the films buried in FS but not for the films buried in FSst and in MS. However, no changes were observed for the melting temperature, glass transition temperature, monomer compositions, structure, and functional group analyses of the films from any of the burial sites during the test period. This means that the integral properties of the films were maintained during that period and degradation was by surface erosion. Scanning electron microscopy of the films from the three sites revealed holes on the film surfaces which could be attributed to attack by microorganisms and bigger organisms such as detritivores. For comparison purposes, films of polyhydroxybutyrate (PHB), a short-chain-length PHA, and polyethylene (PE) were buried together with the PHAMCL films in all three sites. The PHB films disintegrated completely in MS and lost 73.5% of their initial weight in FSst, but only 4.6% in FS suggesting that water movement played a major role in breaking up the brittle PHB films. The PE films did not register any weight loss in any of the test sites.

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Chemical, enzymatic and microbial degradation of bacterial and synthetic poly-β-hydroxyalkanoates

Cited by 20 publications

References 12 publications

Topotactic crystallization of isolated poly(β-hydroxybutyrate) granules from Alcaligenes eutrophus

Topotactic crystallization of isolated poly(β-hydroxybutyrate) granules from Alcaligenes eutrophus

Microbial Degradation of Poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate) in Soil

Degradation of medium-chain-length polyhydroxyalkanoates in tropical forest and mangrove soils

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