Biodegradable Substances and Biodegradation Processes

Biodegradation can be defined as the biologically-catalyzed reduction of the complexity of a substance. Several conditions must be satisfied for biodegradation to occur  

The population (or biomass) of bacteria or fungi acting on many synthetic compounds is typically small, and therefore the surrounding conditions must allow their proliferation for biodegradation to take place. The occurrence and abundance of microorganisms in an environment are determined not only by the available carbon, but also by physical and chemical factors such as dioxygen and nutrient availability, temperature, pH, salinity, and water activity. 

A xenobiotic is a compound foreign to a particular organism (i.e., it does not participate in its normal biochemistry). A chemical that is normal to one organism may be foreign to another, and so xenobiotics may be natural or synthetic. They may 

There are cases when a substrate is not used for growth, but is metabolized in the presence of a second substrate that is used to support microorganism reproduction. This type of transformation is called cometabolism. Cometabolic conversions that apparently involve a single enzyme include hydroxylations, oxidations, denitrations, deaminations, hydrolyses, acylations, and cleavages of ether bonds. Many of these conversions are complex and involve several enzymes. This may be explained by the existence of enzymes that perform a single type of reaction, but which act on a series of closely related molecules. 

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