PRODUCTION OF POLYHYDROXYALKANOATES, A FAMILY OF BIODEGRADABLE PLASTICS AND ELASTOMERS, IN BACTERIA AND PLANTS

In response to problems associated with plastic waste and its effect o n the environment, there has been considerable interest in the develop ment and production of biodegradable plastics. Polyhydroxyalkanoates ( PHAs) are polyesters that accumulate as inclusions in a wide variety o f bacteria. These bacterial polymers have properties ranging from stif f and brittle plastics to rubber-like materials. Because of their inhe rent biodegradability; PHAs are regarded as an attractive source of no npolluting plastics and elastomers that can be used for specialty and commodity products. The possibility of producing PHAs in large scale a nd at a cost comparable to synthetic plastics has arisen from the demo nstration of PHA accumulation in transgenic Arabidopsis plants express ing the bacterial PHA biosynthetic genes. Synergism between knowledge of the enzymes and genes contributing to PHA synthesis in bacteria and engineering of plant metabolic pathways will be necessary for the dev elopment of crop plants that produce biodegradable plastics.