Novel phosphorylation of aldrin-trans-diol by dieldrin-degrading fungus Mucor racemosus strain DDF

Abstract Dieldrin is one of the most persistent organic pollutants, and its oxidative degradation pathways by aerobic microorganisms to 6,7- trans -dihydroxydihydroaldrin (otherwise known as aldrin- trans -diol) and 9-hydroxydieldrin are well documented. The dieldrin-degrading fungus, Mucor racemosus strain DDF, can decrease dieldrin levels with simultaneous production of a small amount of aldrin- trans -diol. A reduction in the levels of aldrin- trans -diol by strain DDF has also been observed. Based on these results, it has been suggested that strain DDF transforms dieldrin to more polar compounds via aldrin- trans -diol. We have conducted a study to identify the metabolites arising from aldrin- trans -diol. The results showed that strain DDF gave reduced levels of aldrin- trans -diol and also produced unknown metabolites. Ultra performance liquid chromatography-electrospray ionization-mass spectroscopy (UPLC-ESI-MS) analysis indicated the metabolites to be either sulfated- or phosphorylated- derivatives of aldrin- trans -diol, but with the metabolites retaining six chlorine atoms. Therefore, the candidate derivatives were synthesized and the retention times of the natural metabolite and the synthetic phosphate were compared. As a result of a co-injection experiment, the metabolites were determined to be aldrin- trans -diol exo - and endo -phosphates. These results were also supported by high-resolution-fast atom bombardment-mass spectrometry (HR-FAB-MS) of the natural metabolite (Δ = 0.63 ppm). Phosphorylation of aldrin- trans -diol is the first reported example of phosphate conjugation in microorganisms.