ABSTRACT
Microorganisms are well known for their adaptability to extreme environments; although the initial response has been slow, there is now increasing evidence that microorganisms are "learning" to cope with the multitude of toxic, man-made chemicals that have been released into the environment in massive amounts. This chapter reviews some aspects of microbial dissimilation of chlorinated compounds, with particular emphasis on the role of plasmids in such processes, and genetic mechanisms governing dissimilation of chlorinated compounds by members of Enterobacteriaceae. The presence of chlorine atoms on the aromatic nucleus is known to greatly retard the chemical reactivity, particularly towards the electrophilic form of oxygen which is involved before ring cleavage can take place. Screening of bacterial cultures from soil or aquatic samples contaminated with waste or crude oil for their ability to degrade hydrocarbons usually demonstrates this ability to be confined to certain aerobic bacterial genera, fungi, and some actinomyces.
