Estradiol improves tributyltin degradation by the filamentous fungus Metarhizium robertsii

• The fungus Metarhizium robertsii was able to metabolize tributyltin and 17β-estradiol.
• TBT biotransformation rate in the presence of estradiol was increased.
• E2 protects fungal cells against TBT toxicity.
• Estradiol and TBT had a different influence on M. robertsii lipids.

Tributyltin chloride (TBT) is a toxic and persistent organic pollutant that is extensively employed in a variety of industrial products. TBT, an endocrine disrupting chemical, disturbs lipids homeostasis in living cells and is responsible for generating reactive oxygen species (ROS), which affect cell viability. The aim of this study was to test whether estradiol (E2), which exhibits antioxidant activity, could increase the TBT degradation efficiency by the filamentous fungus Metarhizium robertsii. After five days of incubation in Sabouraud growth medium, 27% of TBT (added at the initial concentration 2.5 mg l−1) was converted to dibutyltin (DBT) and monobutyltin (MBT). The data obtained for fungal cultures incubated with TBT and E2 simultaneously demonstrated that, in the presence of estradiol, the TBT-induced growth inhibition was reduced and 44% of TBT was metabolised. Moreover, the determination of phospholipids and the assessment of propidium iodide influx showed a strong disturbance in the membrane integrity and the phosphatidylcholine (PC)/phosphatidylethanolamine (PE) ratio for TBT-stressed mycelia, whereas fungal cells treated with the mixture of TBT and E2 presented a lower level of membrane disintegration. It is suggested that E2 protects fungal cells against TBT toxicity and improves biocide degradation.