Electron microscopy has revealed that degradation occurs at the surface by enzymatic hydrolysis (surface erosion).
The molecular weights of PHA samples remained almost unchanged during the course of biodegradation.
A number of microorganisms such as bacteria and fungi in soil, sludge, and sea water excrete extracellular PHA-degrading enzymes to hydrolyze the solid PHA into water-soluble oligomers and monomer, and subsequently utilize the resulting products as nutrients within cells.