Impact of Bis-O-dihydroferuloyl-1,4-butanediol Content on the Chemical, Enzymatic and Fungal Degradation Processes of Poly(3-hydroxybutyrate) (original) (raw)
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Agro industrial residues considered as agro-wastes, generated during the processing of crops are produced in large quantities every year worldwide. Major quantities of these on-farm agricultural residues are burnt in the field itself. Polyhydroxybutyrate (PHB), well known macromolecule naturally produced by many species of microorganisms, is being considered as a replacement for conventional plastics; however, the major drawback in PHB commercialization falls due to its high production cost. In the present study agro residues such as wheat bran and rice bran were studied as a cost effective substrate for the replacement of carbon source for the production of PHB using B. subtilis. The agro residues were initially hydrolyzed; different concentrations were amended in the minimal salt medium and investigated for PHB production. Several parameters such as incubation time, pH, temperature were optimized prior to the addition of agro residues for the production of PHB. The PHB produced were partially purified and further characterized using FTIR analysis. The results showed that the agro residues are found to be potential suitable substrate for the replacement of carbon source during the production of PHB.
Polymer testing, 2004
The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (PHB-V) was assessed by the loss of mass, tensile strength and roughness of the polymer. The melting temperature and crystallinity were also determined. Both polymers showed similar biodegradation in soil composting medium at 46°C and at room temperature (24°C) and in a soil simulator. PHB-V had the lowest crystallinity values and PHB had the highest. Soil composting medium at 46°C favoured the biodegradation of PHB and PHB-V based on the loss of mass. After ageing in soil composting medium at 46°C for 86 days, both polymers showed a decrease in the tensile strength at break (76% for PHB and 74% for PHB-V). In agreement with this, the roughness of both polymers increased faster in soil composting medium at 46°C. These results suggest that roughness may be a useful parameter for evaluating the biodegradation of polymers.
Polymer Testing, 2004
The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (PHB-V) was assessed by the loss of mass, tensile strength and roughness of the polymer. The melting temperature and crystallinity were also determined. Both polymers showed similar biodegradation in soil composting medium at 46°C and at room temperature (24°C) and in a soil simulator. PHB-V had the lowest crystallinity values and PHB had the highest. Soil composting medium at 46°C favoured the biodegradation of PHB and PHB-V based on the loss of mass. After ageing in soil composting medium at 46°C for 86 days, both polymers showed a decrease in the tensile strength at break (76% for PHB and 74% for PHB-V). In agreement with this, the roughness of both polymers increased faster in soil composting medium at 46°C. These results suggest that roughness may be a useful parameter for evaluating the biodegradation of polymers.
Biodegradation
Biodegradation rates and mechanical properties of poly(3-hydroxybutyrate) (PHB) composites with green algae and cyanobacteria were investigated for the first time. To the authors knowledge, the addition of microbial biomass led to the biggest observed effect on biodegradation so far. The composites with microbial biomass showed an acceleration of the biodegradation rate and a higher cumulative biodegradation within 132 days compared to PHB or the biomass alone. In order to determine the causes for the faster biodegradation, the molecular weight, the crystallinity, the water uptake, the microbial biomass composition and scanning electron microscope images were assessed. The molecular weight of the PHB in the composites was lower than that of pure PHB while the crystallinity and microbial biomass composition were the same for all samples. A direct correlation of water uptake and crystallinity with biodegradation rate could not be observed. While the degradation of molecular weight of ...
Polymer Degradation and Stability, 2004
Biodegradation studies of binary blends of bacterial poly(hydroxybuyrate-co-hydroxyvalerate) (PHB-21%HV) with synthetic poly(2-hydroxyethylmetacrylate) (PHEMA) prepared by casting were performed. The compositions were explored in a range of 20-50% PHEMA on PHBHV. ASTM G21-90 including measurements of CO 2 were used to determine biodegradability. The time required for biodegradation increased as PHEMA content in the blend increased. Although all blends were biodegradable, as determined by ASTM G21-90 method, the CO 2 measurements could be indicative that the degradation of PHEMA, if it exists, is limited. Degradation of blends attained 90% (mass loss) in a period from 7 to 15 days, though after 30 days no degradation was detectable when PHEMA was tested as a single component. Penicillium funiculosum showed the highest degradation activity among five fungal species tested for biodegradation. Microscopic studies show that biodegradation of blends started at their surface.
Mechanism and kinetics of the hydrolytic degradation of amorphous poly(3-hydroxybutyrate)
Polymer Degradation and Stability
Amorphous poly(3-hydroxybutyrate) films prepared by compression molding and solvent casting were degraded in aqueous media at different pH values. The time dependence of degradation was monitored by the measurement of weight loss, the extraction of the degradation products from the degrading sample, as well as by UV-Vis spectrophotometry and HPLC analysis of the aqueous solution. The results proved that degradation takes place mainly in the bulk of the samples and not on their surface. The overall rate of degradation depends strongly on pH; it increases with increasing pH values. Metabolite extraction and chromatography proved that degradation does not occur randomly, but with larger frequency at the end of the chains. By assuming that the hydrolysis of PHB is a SN2 type nucleofil substitution reaction, a kinetic model was proposed which describes the formation of various degradation products. The diffusion of metabolites was also accommodated into the model thus the concentration in the aqueous solution could also be predicted well. The correlation between prediction and experimental results is excellent. The model can be extended also for the description of the hydrolytic degradation of other aliphatic polyesters. 1 INTRODUCTION Poly(3-hydroxybutyrate) (PHB) is one of the most important biopolyesters from the family of polyhydroxyalkanoates which are produced by microorganisms from renewable resources [1-7]. Unlike in the synthetic polymerization of PHB, the production of the biopolymer by microbial fermentation excludes the presence of toxic products [8-10] and the hydrolytic degradation of PHB leads mainly to the monomer D-3-hydroxybutyric acid. This acid is a normal component of blood and is one of the three ketones which are
International Journal of Biological Macromolecules, 2019
Biodegradable poly-3-hydroxybutyrate [P(3HB)] and natural materials (fillers)clay, peat, and birch wood powderwere used to prepare powdered blends and, then, pellets and granules. Pellets were produced by cold pressing of polymer and filler powders; granules were produced from the powders wetted with ethanol. Properties of initial P(3HB) and fillers and blends thereof were studied using IR spectroscopy, DSC, X-ray analysis, and electron microscopy. No chemical bonds between the components were revealed: the blends were physical mixtures. The degree of crystallinity of the blends was lower than that of the initial polymer, suggesting different crystallization kinetics of the blends. Introduction of increasing amounts of the fillers into the polymer progressively decreased mechanical strength of the pellets, as confirmed by the decrease in Young's modulus. The study of degradation of the blends in soil showed that the mass loss of the blends over 35 days of incubation in soil varied between 30 and 50% of the initial mass of the products, depending on the type of the filler.
Applied Environmental Biotechnology, 2017
Degradability of syndiotactic poly ([R]-β-hydroxybutyrate) (syn-PHB), a chemically synthesized PHB, was investigated in this study by incubation of the polymer films in a soil of northeastern China. During incubation, progressive weight loss of the syn-PHB films and a corresponding decrease of molecular weight were observed over the 90 days of incubation indicating the biodegradation of syn-PHB and a random cleavage of the ester bonds. Microorganisms isolated and identified from the partially degraded films included Pseudomonas spp., Alcaligenese sp., and Comamonas sp.. Our results suggest that chemically synthesized syn-PHB is biodegradable under aerobic conditions in soil.
International Journal of Molecular Sciences
Due to increased environmental pressures, significant research has focused on finding suitable biodegradable plastics to replace ubiquitous petrochemical-derived polymers. Polyhydroxyalkanoates (PHAs) are a class of polymers that can be synthesized by microorganisms and are biodegradable, making them suitable candidates. The present study looks at the degradation properties of two PHA polymers: polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-polyhydroxyvalerate (PHBV; 8 wt.% valerate), in two different soil conditions: soil fully saturated with water (100% relative humidity, RH) and soil with 40% RH. The degradation was evaluated by observing the changes in appearance, chemical signatures, mechanical properties, and molecular weight of samples. Both PHB and PHBV were degraded completely after two weeks in 100% RH soil conditions and showed significant reductions in mechanical properties after just three days. The samples in 40% RH soil, however, showed minimal changes in mechan...
Surface composition and morphology of poly(3-hydroxybutyrate) exposed to biodegradation
Polymer Testing, 2008
Injected samples of poly(3-hydroxybutyrate) (PHB) were exposed to biodegradation in simulated soil and then characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), roughness and weight loss. The decomposition medium was evaluated by measurements of pH, humidity and amounts of carbon and nitrogen. The weight loss test indicated a significant weight decrease with time, which was more intense in the first 3 months of biodegradation. The results obtained by means of XPS, SEM, DSC and roughness analyses suggested a possible layer-by-layer degradation process having a 3-month period. r