FAQs
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PHA is a family of biological polyesters that is synthesized and stored as water insoluble inclusions in various microorganisms, under nutrient-limited conditions in the presence of excess carbon source.
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DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. It can be used to observe fusion and crystallization events as well as glass transition temperature (Tg). The melting temperature (Tm) and enthalpy of fusion (∆Hm) of PHA can also be determined.
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Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of ions. It is most generally used to find the composition of a physical sample by generating a mass spectrum representing the masses of sample components. Thus, the isotopic composition of elements and the structure of PHA can be determined by observing its fragmentation.
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One-stage cultivation: A single-stage process developed for PHA accumulation by growth associated PHA production strains
Two-stage cultivation: A two-stage process developed for PHA accumulation by non-growth associated PHA production strains
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Yes. The molecular weight of P(3HB) produced by eukaryotes is lower, ranging from 100 to 150 3HB monomer units.
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In eukaryotes, P(3HB) helps to control the permeability of cells to minerals while in prokaryotes, P(3HB) functions as carbon and energy storage.
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Inoculum is the seed culture for PHA production, which is the amount of cells used to produce more cells (usually 3-10 % [v/v] of the culture medium).
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Substrate specificity is when an enzyme is active towards certain substrates but has low activity towards other substrates.
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The PHA synthase of R. eutropha is specific towards C3, C4 and C5 scl-monomers, but a very small amount of C6, C8 and C10 mcl-monomers can also be polymerized.
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PHA synthases (PhaCs) have been grouped into four classes based on their primary amino acid sequences, substrate specificity and subunit composition. Class I and II PhaCs consist of a single PhaC subunit but prefer scl and mcl substrates, respectively. Meanwhile, both class III and IV PhaCs have similar substrate preference for scl monomers but require extra subunits termed PhaE and PhaR, respectively, for full functionality.
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Sudan Black B can be used to stain native PHA inclusions. Nile Blue A more specifically stains the inclusions and exhibits strong orange fluorescence. Meanwhile, Nile Red can detect PHA directly in growing bacterial colonies.
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Nucleic acids: ribonucleic acids, deoxyribonucleic acids.
Polyamides: proteins and poly(amino acids)
Polysaccharides: cellulose, starch, xanthan.
Organic polyoxoesters: PHA, poly(malic acid), cutin
Polythioesters: recently reported.
Inorganic polyesters with polyphosphate.
Polyisoprenoids: natural rubber of Gutta Percha.
Polyphenols: lignin, humic acids. -
RCF = (rpm)2 × 1.118 × 10-5 × rotational radius in centimeter
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Any foreign substances or exogenous chemicals which the body does not recognize such as drugs, pollutants, as well as some food additives and cosmetics.
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Any foreign substances or exogenous chemicals which the body does not recognize such as drugs, pollutants, as well as some food additives and cosmetics.
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A high biocompatibility is essential for the acceptance of an incorporated object by humans and mammals. Several factors to determine whether an object is biocompatible:
- Shape
- Surface porosity
- Chemistry of the materials
- Environment (tissue) where it is incorporated
(Traditionally used materials, e.g. silicone, are suspected to cause cancer. Thus, PHA has the potential to become an important compound for medical applications)
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- Biocompatibility
- Support of cell growth and cell adhesion
- Guide and organize the cells
- Allow ingrowth of cells and passage of nutrients and waste products
- Biodegradable without formation of toxic compounds
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A thermoplastic melts to a liquid when heated and freezes to a brittle state when cooled sufficiently. Thermoplastics are elastic and flexible above the glass transition temperature (Tg), can go through melting/freezing cycles repeatedly, and can be reshaped upon reheating.
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The side chain of mcl-PHA is much longer compared to that of scl-PHA, and cannot be arranged in a compact manner inside the mcl-PHA granules, thus resulting in a lower density.