increases in environmental contamination lead to a progressive deterioration of environmental quality . 
 this condition challenges our global society to find effective measures of remediation to reverse the negative conditions that severely threaten human and environmental health . 
 we discuss the progress being made toward this goal through application of bioremediation techniques . 
 bioremediation generally utilizes microbes ( bacteria , fungi , yeast , and algae ) , although higher plants are used in some applications . 
 new bioremediation approaches are emerging based on advances in molecular biology and process engineering . 
 bioremediation continues to be the favored approach for processing biological wastes and avoiding microbial pathogenesis . 
 bioremediation may also play an increasing role in concentrating metals and radioactive materials to avoid toxicity or to recover metals for reuse . 
 microbes can biodegrade organic chemicals ; purposeful enhancement of this natural process can aid in pollutant degradation and waste - site cleanup operations . 
 recently developed rapid - screening assays can identify organisms capable of degrading specific wastes and new gene - probe methods can ascertain their abundance at specific sites . 
 new tools and techniques for use of bioremediation in situ , in biofilters , and in bioreactors are contributing to the rapid growth of this field . 
 bioremediation has already proven itself to be a cost - effective and beneficial addition to chemical and physical methods of managing wastes and environmental pollutants . 
 we anticipate that it will play an increasingly important role as a result of new and emerging techniques and processes.imagesfigure 3 .