Opportunities for using microorganisms in this way mushroomed as scientists discovered there's practically nothing that can't be viewed as food by one microbe or another. Just as some insects can feed on leaves that are toxic to others, so some microbes can thrive on molecules that would poison most organisms. There are microbes that feed on such toxic materials as methylene chloride, detergents, creosote, pentachlorophenol, sulfur, and polychlorinated biphenyls (PCBs).

The biotreatment of methylene chloride, a suspected carcinogen, is one of the big success stories in this field. Produced by various industrial processes in quantities of millions of pounds each year, methylene chloride can be almost completely eliminated at its source by passing