BIOSYNTHESIS OF POLYESTERS IN BACTERIA AND RECOMBINANT ORGANISMS

Many bacteria are able to synthesize polyesters of hydroxyalkanoic aci ds (PHA), which occur as insoluble cytoplasmic inclusions in the cell and can contribute significantly to the cellular dry matter. More than 100 different hydroxyalkanoic acids have been detected as constituent s in PHA. This article summarizes strategies and possibilities to obta in these biodegradable and thermoplastic/elastomeric polymers by ferme ntation of wild-type bacteria as well as of mutants and recombinant st rains from renewable resources, waste substrates or special precursor substrates. In addition, in vitro biosynthesis of PHA employing the pu rified polymerizing enzyme (PHA synthase) is described. Throughout ana lysis and cloning of the bacterial PHA biosynthesis genes enabled scie ntists to also establish this pathway in non-PHA producing eukaryotic organisms such as yeast, plants and animals. This will allow new proce sses for cheap and economic production of PHA. (C) 1998 Elsevier Scien ce Limited. All rights reserved.