ABSTRACT
Many toxic substances are decomposed or altered by microorganisms because that ability gives them an advantage in their natural environment. Many organic hazardous wastes are degraded by microorganisms in a series of enzyme catalyzed reactions. Strategies for genetic improvement of microorganisms can be as simple as exposing a bacterium to a mutagen like nitrogen mustard and screening on agar plates for survivors that appear to grow faster on an organic waste or display a higher resistance to a heavy metal. These genetically improved strains can then be subjected to additional rounds of treatment and screening. Recently, the technique of site directed mutagenesis has been used to markedly increase the stability of the commercially useful enzyme subtilisin. While this particular enzyme has limited application in hazardous waste degradation, it serves as an example of what can be done using modern genetic strategies for improving the stability of enzymes that have cloned and well characterized genes.
