Physico-chemical properties of polyhydroxyalkanoate produced by mixed-culture nitrogen-fixing bacteria

Patel, Meeta; Gapes, Daniel J.; Newman, Roger H.; Dare, P. H.

doi:10.1007/s00253-008-1836-0

Cited by 52 publications

(62 citation statements)

References 48 publications

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“…[24][25][26][27] For the PHA/PA blends, the fracture surface morphology was investigated for the different weight ratios (20/80, 50/50, and 80/20). The facture morphologies of specimens after tensile testing are shown in Figure 1(a).…”

Section: Resultsmentioning

confidence: 99%

Characterization and biodegradation behavior of bio-based poly(lactic acid) and soy protein blends for sustainable horticultural applications

et al. 2015

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Adipic anhydride-plasticized soy protein (SP.A) was blended with poly(lactic acid) (PLA) at two concentrations (50/50 and 33/67) and was evaluated for use as a sustainable replacement for petroleum plastic in horticulture crop containers. Following the discovery that SP.A/PLA blends provide additional functions above that of petroleum plastic for this application, the present study evaluates the biodegradation behavior of these materials in soil and describes the substantial improvements in sustainability that result from the additional functions (intrinsic fertilizer and root improvement of plants) and the end-of-life option of biodegradation. After being buried in soil for designated time intervals, the residual degraded samples were analyzed to determine morphological and thermal properties at sequential stages of biodegradation. Samples were characterized by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results indicated that there was a compatible system between SP.A and PLA in the melt. Incorporation of SP.A accelerated the biodegradation rate of this binary blend significantly compared with pure PLA. Prior to the degradation process, both the glass transition temperatures and melting temperatures of the blends containing SP.A decreased as the concentration of the soy protein increased. With increasing degradation time of the blended samples in soil, the glass transition temperatures increased in the early stages of biodegradation then decreased, a trend associated with the decrease in the molecular weight of the blends as a result of biodegradation. In addition, the thermal stability of blends increased gradually with increasing degradation time, suggesting faster biodegradation loss of the soy component of the SP.A/PLA blends. These results support the use of soy-based polymer blends for horticulture crop containers and provide data for evaluating their use as sustainable materials for other potential applications. Disciplines ABSTRACTOne of the most significant limitations to widespread industrial implementation of emerging bioplastics such as poly(lactic acid) and poly(hydroxyalkanoate) (PHA) is that they do not match the flexibility and impact resistance of petroleum-based plastics like poly(propylene) or highdensity poly(ethylene). The basic goal of this research is to identify alternative, affordable, sustainable, biodegradable materials that can replace petroleum-based polymers in a wide range of industrial applications, with an emphasis on providing a solution for increasing the flexibility of PHA to a level that makes it a superior material for bioplastic nursery-crop containers. A series of bio-based PHA/poly(amide) (PA) blends with different concentrations were mechanically melt processed using a twin-screw extruder and evaluated for physical characteristics. The effects of blending on viscoelastic properties were investigated using smallamplitude oscillatory shear flow experimen...

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Section: Resultsmentioning

confidence: 99%

Characterization and biodegradation behavior of bio-based poly(lactic acid) and soy protein blends for sustainable horticultural applications

et al. 2015

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“…44 % followed by copolymers with varying monomer composition e.g. 40 % index for P(3HB:30 % 3HV) [87]. P(3HB:8 % 3HV) has the crystallanity index of 57.3 % which decreases to 44 % in polymer with 15-18 mol% of 3HV content [82].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

et al. 2015

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Polyhydroxyalkanoates (PHAs) as an alternative to synthetic plastics have been gaining increasing attention. Being natural in their origin, PHAs are completely biodegradable and eco-friendly. However, consistent efforts to exploit this biopolymer over the last few decades have not been able to pull PHAs out of their nascent stage, inspite of being the favorite of the commercial world. The major limitations are: (1) the high production cost, which is due to the high cost of the feed and (2) poor thermal and mechanical properties of polyhydroxybutyrate (PHB), the most commonly produced PHAs. PHAs have the physicochemical properties which are quite comparable to petroleum based plastics, but PHB being homopolymers are quite brittle, less elastic and have thermal properties which are not suitable for processing them into sturdy products. These properties, including melting point (T m ), glass transition temperature (T g ), elastic modulus, tensile strength, elongation etc. can be improved by varying the monomeric composition and molecular weight. These enhanced characteristics can be achieved by modifications in the types of substrates, feeding strategies, culture conditions and/or genetic manipulations.

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“…Several of these species have also been found to produce polyhydroxyalkanoate (PHA) (1,4,6), which represents a class of polymers with properties comparable to those of petroleum-derived plastics (2). The potential of diazotrophic bacteria that can use waste-derived feedstocks to help lower the cost of PHA production is an active area of research (8). Sphingomonads can potentially serve as PHA production strains in nitrogen-poor waste stream substrates, based on their abilities to thrive in such environments.…”

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Draft Genome Sequence of Novosphingobium nitrogenifigens Y88T

Strabala

Macdonald

Liu

et al. 2011

Journal of Bacteriology

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Novosphingobium nitrogenifigens was originally isolated from pulp and paper mill wastewater, a low-nitrogen, high-carbon environment. N. nitrogenifigens is the first known nitrogen-fixing, polyhydroxyalkanoate-accumulating sphingomonad, and we report the annotated draft genome sequence of the type strain Y88 T here. Sphingomonad bacteria are often found in high-carbon, lownitrogen, environmentally degraded habitats and/or are capable of metabolizing various industrial pollutants as carbon sources (1,5,6,9). Several of these species have also been found to produce polyhydroxyalkanoate (PHA) (1, 4, 6), which represents a class of polymers with properties comparable to those of petroleum-derived plastics (2). The potential of diazotrophic bacteria that can use waste-derived feedstocks to help lower the cost of PHA production is an active area of research (8). Sphingomonads can potentially serve as PHA production strains in nitrogen-poor waste stream substrates, based on their abilities to thrive in such environments.Novosphingobium nitrogenifigens Y88 T is a Gram-negative, obligate aerobe sphingomonad that was originally isolated from nickel-enriched pulp and paper mill wastewater (1). N. nitrogenifigens is capable of nitrogen fixation and production of poly-3-hydroxybutyrate (PHB). N. nitrogenifigens has also proven effective in the removal of Mn and Zn from model biorefinery effluent (A. Palumbo et al., submitted for publication). These metabolic properties led us to further explore the characteristics of this organism aided by its genome sequence.The draft genome of N. nitrogenifigens Y88 T (ICMP 16470 T , DSM 19370 T ) was obtained via Roche 454 pyrosequencing (454 Life Sciences, Branford CT) combining 454 GS 20 and 454 GS FLX Titanium paired-end sequencing (1,151,296 quality reads). Using Newbler 2.3 (454 Life Sciences), these reads were assembled into 19 scaffolds comprising 77 contigs at 60-fold coverage, totaling 4.14 Mbp. GϩC content was 63%. Annotation of predicted coding sequences (CDS) was performed using Glimmer version 3.02 (3), which identified 3,801 putative protein-coding genes. Of these CDS, 1,056 were identified as hypothetical/unknown function predicted proteins. Additionally, 49 tRNA genes were identified using the stand-alone version of tRNAscan-SE, v1.23 (7).Two small, related plasmids named py8 (5,911 bp) and py157 (5,720 bp) were also identified and independently confirmed (Quanfeng Liang and Gareth Lloyd-Jones, unpublished results). In contrast to the genome sequence, 363-fold (py8) and 465-fold (py157) coverage of the plasmids was achieved. The GϩC content of both plasmids was 58%. Neither of the plasmids harbored any CDS similar to known genes other than rep, mob, and traA genes, involved in plasmid conjugation and replication functions. Interestingly, these genes and a number of hypothetical CDS possess the greatest similarity to CDS in Sphingobium japonicum UT26S plasmid pUT2 (GenBank accession no. AP010807), a molecule with a molecular weight similar to those of py8 and py157.As expec...

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Physico-chemical properties of polyhydroxyalkanoate produced by mixed-culture nitrogen-fixing bacteria

Cited by 52 publications

References 48 publications

Characterization and biodegradation behavior of bio-based poly(lactic acid) and soy protein blends for sustainable horticultural applications

Characterization and biodegradation behavior of bio-based poly(lactic acid) and soy protein blends for sustainable horticultural applications

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

Draft Genome Sequence of Novosphingobium nitrogenifigens Y88T

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