Estrogenic activity of bio-degradation products of C-heavy oil revealed by gene-expression profiling using an oligo-DNA microarray system

Degradation of heavy oil by bacteria to decompose organic compounds such as aliphatic and aromatic hydrocarbons has been used in bioremediation. However, the biological and environmental effects of the degradation products including intermediates are still not clear. Here, we monitored the degradation of C-heavy oil by analyzing the products formed in cultures with oil-degrading bacteria (complex microbes or a single bacterial strain). Furthermore, proliferation assays using breast cancer MCF-7 cells and gene-expression profiling of MCF-7 cells using oligonucleotide-DNA microarrays were performed to evaluate the estrogenic activity of the degradation products. While the products did not show any significant cell-proliferative activity, the oil samples cultured for longer periods (2-3 months), whether cultured with mixed microbes or a single bacterial strain, showed gene-expression profiles similar to that of 17β-estradiol (E2). These results suggest that oil-degradation products have estrogenic activity, and estrogen-like components could possibly be produced during the degradation process.

► Oligonucleotide-DNA microarrays were used to monitor bio-degradation of C-heavy oil. ► The oil samples showed gene-expression profiles similar to that of 17β-estradiol. ► Estrogen-like components were produced during the degradation process. ► The effect of bio-degradation products on ecosystems needs more attention. ► DNA microarray assays may be useful for monitoring such products.