Degradable synthetic polymers have generally been those which have linkages found in natural polymers. These include amide, urea, urethane and ester bonds. The polyester, polycaprolactone (PCL) has been used as a model compound to examine some of the biochemical events involved in the process. A variety of microorganisms have been isolated capable of degrading PCL and several selected for further study. The extracellular enzyme system of the yeast Cryptococcus laurentii consists of a constitutive enzyme with a molecular weight (MW) of 23,000 and a low MW cofactor bound to it by non-covalent bonds. It is inactivated at 42 degrees C, has a broad pH optimum between pH 7 and 11, and an isolectric point of pH7.3. The extracellular enzyme system of Pseudomonas aeruginosa consists of a constitutive enzyme with a MW of 20,000 with an aggregate or larger form possible. The pH optimum is sharp at 7.3 and the isoelectric point is pH 5.5