ATP-TOX system—a new,rapid, sensitive bacterial toxicity screening system based on the determination of ATP

A new toxicity screening test, based on the inhibition of bacterial growth and luciferase activity by toxicants was developed. In the ATP-TOX System, chemical toxicity was found to be time-dependent and increased with increasing exposure time up to 5 hours. Three organisms were evaluated in this study: E. coli K-12 PQ37, Pseudomonas fluorescens and Salmonella typhimurium. E. coli K-12 PQ37 was found to be the most sensitive organism. It was also shown that P. fluorescens was more sensitive to toxicants when grown in minimal medium than in nutrient broth, suggesting that nutrients may have a protective effect on the bacterium. In comparative studies using selected toxic chemicals the ATP-TOX System was found to be more sensitive than the Spirillum volutans test and comparable to the Microtox test. Toxicant activity in sediment samples was found to be time dependent and increased with increasing exposure time in both ATP-TOX (E. coli) System and Microtox. The ATP-TOX System is complementary to the Microtox test as it also provides indications of low grade toxicant activity which is only manifested in actively growing cells over several life cycles. Thus, the ATP-TOX System appears to be an ideal screening test for sediment toxicity. The data indicate that the ATP-TOX System is sensitive, rapid, reproducible, economical and has great potential in applied studies.