Polyhydroxybutyrate (PHB) - trade name Biopol
- A bacterial plastic
- Originally made from the Alcaligenes eutrophus bacterium
- However, recent research as looked at making the plastic from GM E coli because E coli grows and replicates much quicker
- A. eutrophus is grown on a high nitrate and phosphate environment to stimulate growth at 30C
- The nutrients that the bacteria are given are then suddenly changed, causing them to produced BHP as an energy source
- After the bacteria grow and produced BHP, the bacteria and nutrient mixture is chemically treated and filtered to remove the BHP, which comes out as a fine white powder
Properties of PHB:
-thermoplastic
-biodegradable in anaerobic landfill conditions
-stable in everyday aerobic conditions
-biocompatible, making it useful in surgical stitches because it dissolves in the body over time without being toxic
-brittle
Uses of PHB:
- stitches
- plastic shampoo/milk bottles
- fishing lines,razors, cutlery,disposable bags, plastic plates
Future potential:
- doesnt have mainstream use because it is not as cheap to produce as plastics made from petrochemicals
- however, its biodegradable and renewable nature gives it potential if weaknesses can be overcome
- waste produced from the process is a disposal issue
Research:
-1992: team at Michican state university inserted a gene from A eutrophus into a the dna of cress plants, producing a plant that grows PHA plastic
- Research has also resulted a gene from A eutrophus being inserted into E coli, causing GM E coli to produce BHA. This is useful because E coli grow and reproduce at a more rapid rate
- Research is ongoing in order to make the process faster and cheaper to compete with plastics derived from petrochemicals