Summary
Various bacterial species accumulate intracellular polyhydroxyalkanoates
(PHAs) granules as energy and carbon reserves inside their cells. PHAs are biodegradable,
environmentally friendly and biocompatible thermoplastics. Varying
in toughness and flexibility, depending on their formulation, they can be
used in various ways similar to many nonbiodegradable petrochemical plastics
currently in use. They can be used either in pure form or as additives to oilderived
plastics such as polyethylene. However, these bioplastics are currently
far more expensive than petrochemically based plastics and are therefore used
mostly in applications that conventional plastics cannot perform, such as medical
applications. PHAs are immunologically inert and are only slowly degraded
in human tissue, which means they can be used as devices inside the body.
Recent research has focused on the use of alternative substrates, novel extraction
methods, genetically enhanced species and mixed cultures with a view to
make PHAs more commercially attractive.