Polychlorinated Biphenyls (Aroclor 1242): Effects of Uptake on E. coli Growth

Polychlorinated biphenyls (PCBs), similar to DDT in structure and physiological effects (7), are of concern to the scientific community because of their ubiquity (8), persistence (11) and possible toxicity. The alleged lack of biodegradability of this environmental pollutant has caused alarm and curtailment of this useful chemical. Work as early as 1963 by Cope (3) indicated that DDT, another chlorinated hydrocarbon, might be metabolized by several species of bacteria. Subsequently, other workers (2, 4, 9, 10) reported degradation of this insecticide by bacteria, fungi, and marine diatoms. Unpublished work performed in our laboratory (5) also indicated possible metabolism of certain PCB components by Cylindrotheca closterium. With the thesis established that DDT was indeed biodegradable and with evidence that PCBs may be biologically converted, the authors postulated that human flora may play an important part in the metabolism of DDT, PCBs, and other ecological contaminants. Experiments were performed to study the effects of PCBs in vitro on a facultative organism, E. coli, common to human intestinal flora. This bacterium was also selected because it is the prime indicator of fecal contamination.