By Janet Raloff
Patrick K. Jjemba was curious about the interplay of protozoa and the bacteria they eat in soil. As part of his research, he began altering the organisms’ environment. When he applied large amounts of protozoan-killing antibiotics to dirt around the roots of soybeans, Jjemba was amazed at what happened. The drugs—widely used in human and veterinary medicine—did far more than subtly alter the balance of microbial predators and prey. One drug stunted soybeans, and another killed the plants.
The University of Cincinnati microbiologist realized he was sailing into largely uncharted waters. Though a growing body of research has documented the presence of antibiotics in the environment, most concerns have focused on what harm these antimicrobials might pose to people, fish, or aquatic birds (SN: 3/23/02, p. 182: Available to subscribers at A Confluence of Contaminants: Streams’ organic mix may pose environmental risk). These drugs, excreted by people and livestock treated with them, enter open waters primarily from sewage effluent and farm runoff.