During degradation, the polymer is first converted to its
monomers, and then these monomers are mineralized. Most
polymers are too large to pass through cellular membranes, so
they must first be depolymerized to smaller monomers before
they can be absorbed and biodegraded within microbial cells.
The initial breakdown of a polymer can result from a variety
of physical and biological forces (Swift 1997). Physical
forces, such as heating/cooling, freezing/thawing, or wetting/
drying, can cause mechanical damage such as the cracking of
polymeric materials (Kamal and Huang 1992). The growth of
many fungi can also cause small-scale swelling and bursting, as
the fungi penetrate the polymer solids (Griffin 1980). Synthetic