DEGRADATION AND APPLICATIONS OF POLYHYDROXYALKANOATES

A series of tests is available to study the biodegradation of plastic materials under either laboratory or field conditions. Most of the standard methods have been published by the American Society for Testing and Materials. All of them describe techniques to investigate the biodegradation of plastics under laboratory conditions. Microbially formed polyhydroxyalkanoates (PHAs) have been marketed recently as biodegradable plastics. However, currently only a few articles made from PHAs (e.g., bottles) are commercially available. A series of microorganisms (prokaryotes as well as eukaryotes) has been characterized as being able to degrade PHAs. With one exception (llyobacter delafieldii), all of them were isolated from aerobic environments. So far, over 10 different extracellular PHA depolymerases have been purified and characterized. Depolymerases that preferentially attack PHAs with monomer units other than 3-hydroxybutyrate have been found only in Pseudomonas fluorescens and Pseudomonas lemoignei.