straight from my notes :
A biopolymer is a polymeric substance that is made by a living organism a substance that is composed of molecules joined in long chains (polymers) and is produced in living organisms. Proteins and DNA are examples of biopolymers.
PHB PolyHydroxyButyrate, formerly known as polyhydroxybutanoate. ( hydroxybutanoate )
A culture of Alcaligenes eutrophus is placed into a suitable medium and fed appropriate nutrients for it to multiply and rapidly grow into large quantities. The diet is then changed and restricted to a certain nutrient, like nitrogen. This stops the growth of the population of the micro-organisms and makes it start to produce PHB, which it stores in its cell for use later as energy. A separation process is then done to remove the PHB from the microorganism.
PHB has similar properties, physical and mechanical, to polypropylene: it is transparent, brittle, water-proof and lightweight, and would be suitable for bottles and other containers
It is biodegradable, in other words, it can be decomposed and broken down in natural systems like blood and soil without the release of toxins. Hence, it is good for such things like nappies and plastic food wrapping.
PHB monomer is a natural constituent of blood hence it can be used as internal stitching. Since the bacteria in our own stomachs make PHB to store energy our bodies will not reject it. PHB can be used in medicine, where the body gradually replaces PHB over time. The plastic could also be used as a material that slowly releases drugs into the body. After surgical implantation, its gradual degradation releases locked-in drugs, right at the point where they are needed most.
The main advantage of the biopolymer is that it is biodegradable and can break down in our environment. A second environmental advantage would be that when PHBs decompose, they do not release harmful toxins.
The US Navy has opted to use PHB cups so that sailors can throw them into the sea. In Japan, PHB has found its way into people's bathrooms and appears in the form of disposable razors. The discretion surrounding the whole activity requires that the razors be thrown down a toilet, and instantly flushed away. PHB's rapid degradation in sewage clearly makes it the right choice.
PHB itself exists in the cells of a staggering variety of different organisms.
There are a few disadvantages of using the biopolymer. For one, there is not enough technology to improve faster and efficient productions of PHBs. Current methods are very costly.
The environment of the bacteria must be kept and an optimum temperature.
The quality of the product may be inconsistent and the variable patterns of supply will mean price fluctuation and the material itself is rather brittle. Land degradation must be made way to produce the sources for biopolymers as well if demands reach high. Even if biodegradable plastics start to be used now and broadly, waste will not completely disappear. Land-fill sites are infamously bad at enabling anything to degrade. Paper itself lasts decades. There are not enough bacteria because there is not enough oxygen around for them to thrive. Large-scale composting facilities will be needed and these cost money.
PHB is an example of a biopolymer that is currently in development. Its properties as containers and bottles, and its medical uses make it an important plastic. Further, its biodegradability means it is also responsible to the environment and by far, the best alternative to current polymers. The problem of our landfill can be reduced and possibly solved if the introduction of biopolymers starts now. However, technology and production of these biopolymers are in its infancy and further development is needed alongside examining new ways to reduce plastic waste, will ensure that the environment stays protected for future.
name the specific enzyme(s) used or organism used to synthesise the material
