Fe(III) mineral reduction followed by partial dissolution and reactive oxygen species generation during 2,4,6-trinitrotoluene transformation by the aerobic yeast Yarrowia lipolytica


Understanding the factors that influence pollutant transformation in the presence of ferric (oxyhydr)oxides is crucial to the efficient application of different remediation strategies. In this study we determined the effect of goethite, hematite, magnetite and ferrihydrite on the transformation of 2,4,6-trinitrotoluene (TNT) by Yarrowia lipolytica AN-L15. The presence of ferric (oxyhydr)oxides led to a small decrease in the rate of TNT removal. In all cases, a significant release of NO2− from TNT and further NO2− oxidation to NO3− was observed. A fraction of the released NO2− was abiotically decomposed to NO and NO2, and then NO was likely oxidized abiotically to NO2 by O2. ESR analysis revealed the generation of superoxide in the culture medium; its further protonation at low pH resulted in the formation of hydroperoxyl radical. Presumably, a fraction of NO released during TNT degradation reacted with superoxide and formed peroxynitrite, which was further rearranged to NO3− at the acidic pH values observed in this study. A transformation and reduction of ferric (oxyhydr)oxides followed by partial dissolution (in the range of 7–86% of the initial Fe(III)) were observed in the presence of cells and TNT. Mössbauer spectroscopy showed some minor changes for goethite, magnetite and ferrihydrite samples during their incubation with Y. lipolytica and TNT. This study shows that i) reactive oxygen and nitrogen species generated during TNT transformation by Y. lipolytica participate in the abiotic conversion of TNT and ii) the presence of iron(III) minerals leads to a minor decrease in TNT transformation.


Additional file: Table S1. Change of medium pH during aerobic growth of Y. lipolytica AN-L15 and maximum amounts of some metabolites (μM) detected over the course of TNT biotransformation. Table S2. Mössbauer spectroscopic analysis of various ferric (oxyhydr)oxides after their aerobic incubation with Y. lipolytica AN-L15 cells in the absence or presence of TNT. Figure S1. Formation of dissolved Fe(II) during aerobic growth of Y. lipolytica AN-L15 in the presence of different ferric (oxyhydr)oxides (0.15 g L–1 Fe Error bars represent the standard deviation of triplicate experiments.



Ziganshin, Ayrat M, Elvira E Ziganshina, James Byrne, Robin Gerlach, Ellen Struve, Timur Biktagirov, Alexander Rodionov, and Andreas Kappler. “Fe(III) Mineral Reduction Followed by Partial Dissolution and Reactive Oxygen Species Generation During 2,4,6-Trinitrotoluene Transformation by the Aerobic Yeast Yarrowia Lipolytica.� AMB Express 5, no. 1 (2015): 8. doi:10.1186/s13568-014-0094-z.
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