ScholarWorks@UNO

Genotoxicity of Oil Photoproducts in Aqueous Environments

An Ames Test was used to examine the genotoxicity of Macondo and surrogate oil photoproducts. 200 µL of oil on 10 mL of pure water were irradiated at 27 ˚C for 6h to 48h. A 48h dark control was included. The aqueous fraction was collected and filtered. S. typhimurium cultures TA98 and TA100, which test for frameshift and base-pair substitution mutations, were grown for 16h at 37 ˚C. Each sample was tested with both strains as well as with two different treatments. For the first treatment, samples were incorporated with bacterial culture into the top agar before being poured onto minimal media plates. The other treatment included a preincubation of the bacterial culture with the sample for 20 min at 37 ˚C before being mixed with the top agar. Plates were incubated for 48h. A positive control of a known mutagen specific to each bacterial strain was included. Autoclaved water was used as a negative control. All treatments were completed in quadruplicate. After 48h of incubation, the plates were removed and photographed. The center of each plate was imaged and analyzed in ImageJ. Colony counts were checked manually to eliminate automatic counting errors. Results showed an increase in genotoxicity with increasing irradiation time. A vanishing background lawn on plates with preincubation indicated that acute toxicity may also be present under certain conditions. The observed acute toxicity correlated with irradiation time. The results demonstrate that photoproducts exhibit genotoxic effects, potentially impacting the long-term impacts of oil photoproducts in aqueous environments.