Biodegradation and Detoxification of Bisphenol-A by Filamentous Fungi Screened from Nature

Aims: This study demonstrated obtaining fungal isolates able to degrade and reduce the toxicity of Bisphenol-A (BPA).

Study Design: Soils enclosed by; gas stations, paint industries, and pesticides wastes, Cairo, Egypt, will be used for fungal isolation. BPA will be utilized as a sole carbon and energy source for fungal selectivity. Selected fungal strains will be optimized for BPA degradation. The residues of BPA in cultures will be determined. BPA degradation products will be identified. The toxicity of BPA degradation products on in-vitro cell viability of mammalian cell line will be investigated.

Place and Duration of Study: The study was performed in Mycological lab in botany & microbiology department in faculty of science, Al-azhar university and the Regional Center for Mycology and Biotechnology from October 2012 until May 2014.

Methodology: Different types of media shall be used for isolation, identification and purification processes. Determination of BPA concentrations will be assayed by High performance liquid chromatography (HPLC). BPA degradation products will be identified by Gas chromatography–mass spectrometry (GC-MS). Cytotoxicity test will be measured by Mammalian cell line: Vero cells (derived from the kidney of a normal African green monkey).

Results: Six soil samples were collected from different localities contaminated with petroleum and industrial wastes then 52 fungal isolates were purified before screened for BPA degradation. Two promising fungal isolates Aspergillus terreus (C10) and A. flavus (G1) were selected based on their ability to degrade BPA with percentage 50% and 40% respectively. The effect of different conditions on BPA degradation by (C10) and (G1) including nitrogen sources, incubation temperatures, pH and incubation periods were studied. The highest degradation amount of BPA was obtained from isolates (C10) and (G1) using medium containing sodium nitrate at pH 5 and Yeast extract at pH 7 respectively and incubation temp at 30ºC after incubation at 6 days at shaking state. According to GC-mass the BPA degradation products were identified as following compounds; Thiopropionamide, Methanone, (3-amino-2- benzofuryle) (4- chlorophenyle), 1H-pyrazole, 4,5-dihydro-5,5-dimrthyle-4-isoprpylidene, Phenol, 2,4-isopropylidenedi, Phenol, 2,6-bis(1,1-dimethylethyle)-4- (1-methyle-1-phenylethyle), Bis (2-ethylehexyle) phthalate. The toxicity of BPA was reduced after metabolized by selected fungal strains. Toxicity reduction was measured on cell viability of mammalian cell line.

Conclusion: Our results showed that Aspergillus terreus and A. flavus, have ability to degrade BPA and alter it to less toxic products. These products were tested for their toxicity by cytotoxicity test; the test showed hopeful results while compared it with the toxicity of the original compound.