Organism Used to Synthesis the Material: Ralstonia eutrophus (formerly Alcaligenes Eutrophus)
Production:
In industrial production, Ralstonia eutrophus is grown in an environment high nitrates and phosphates that favourable to its growth to create a very large population of bacteria
When a sufficiently large population has been produced, the environment is changed to one that is high in glucose, high in valeric acid and low in nitrogen.
This unnatural high energy dieted environment induces the production of the PHBV copolymer by the bacterium to be natural fat storage material. This process always reduces the colonies numbers greatly.
A large amount of a trichloromethane is added to purify the biopolymer by dissolving the polymer.
The mixture is then centrifuged to remove solid waste
The polymer is extracted from the hydrocarbon solvent as a powder, which is then melted or treated further to create a usable polymer.
Uses in Relation to Properties (Advantages):
• Disposable utensils- biodegradability makes it suitable for single use items where traditional plastics become too soiled to recycle. It is a hard and rigid plastic that is strong enough for cutting and piercing food
• Food packaging film- Its resistance to water provides a moisture barrier and protects food items during transport. Wrapping are discarded so Biopol’s biodegradability reduces landfill waste.
• It is biodegradable, it only takes 2 years to decompose back into natural components. Unlike polyethylene and other petroleum derived plastics; it can be broken down bacteria into carbon dioxide and so will help to reduce levels of rubbish in landfills.
• Can be made into disposable containers for shampoo, cosmetics, and milk bottles as it is non-toxic, insoluble, and has a high tensile strength.
• Dissolvable stitches -It is biocompatible, it is will not rejected by the body’s immune system, and biodegradable, it will be absorbed into the body, use as stitches to prevent tissue scarring after surgery.
Disadvantages:
It is currently very expensive, and currently the demand is not high enough for it to be economically viable
The use of GM bacteria in the production process raises issues of an ethical nature.
There are concerns about the effects of GM bacteria on the environment – e.g. if they escape from cultures.
Analyse progress in the recent development:
There have been many recent developments in Biopol. Biopol is produced from the bacterium Ralstonia eutrophus. However recent gene splicing has been used to transfer the production capability of Ralstonia eutrophus to common Escherichia coli. This has had many various advantages such as:
1. Better yield of the product
2. Faster growth
3. Easier extraction
4. Reduced production of waste biomass
5. It also meant that the bacteria can be extracted from more cost-effective sources. This is mainly from whey, molasses and common agricultural wastes. This would in effect lower the commercial cost Biopol.
The first Biopol produced in industry was significantly brittle. This hampered its usage in common disposable materials and medicine. It was simply not strong enough. However, it was found that an introduction of propanoic acid into the diet of the bacteria (CH3CH2COOH) would produce a much more flexible and widely used polymer. That is why currently the diet of the Biopol producing bacteria is excessive carbon, less nitrogen and propionic acid
