Fungal Bioremediation of the Plasticizer Hazardous Compound di-2-Ethylhexyl Phthalate (DEHP) in Urine and Blood Bags

Abstract

The hazardous compound di-2-ethylhexyl phthalate (DEHP) is widely used as polyvinyl chloride plasticizer. The present research studied the fungal biodegradation of DEHP contained in blood and urine bags. Soil-plate method was used for fungal isolation from heavily plastic polluted soil using Martin’s and Sabouraud’s agar media, where DEHP was the sole carbon source. Isolated fungal species were identified morphologically according to Moubasher (Soil Fungi in Qatar and Arab Countries University of Qatar, Qatar The Center for Scientific and Research, 1993) as Aspergillus nidulans, Aspergillus niger and Rhizopus nigricans. DEHP concentrations were determined in 1 g of soil, urine bags and blood bags to be 0.92, 2.5 and 2.6 g/l, respectively. Samples of both bags (as a sole carbon source) were artificially inoculated with the isolated fungi and incubated for 20 days. As the time increased, the growth increased where Rhizopus nigricans obtained the highest dry weight in urine bags after 20 days of incubation, while A. nidulans had the highest dry weight in blood bags. Also, a sharp declining of initial pH (6.8) reached 4.7 in urine bags with A. niger growth, while reached 2.5 after A. nidulans growth in blood bags. DEHP% decreased as time increased indicating a continuous DEHP utilization by the three fungal species. Aspergillus niger was the most DEHP degrading fungal species in both bags. Scanning electron microscope examination showed an uniform plastic network in both bags before fungal treatment. While, a microporous network was observed on the plastic surfaces in both bags after fungal treatment due to DEHP utilization. The most DEHP metabolizing fungal species were further identified molecularly using internal transcribed spacer primers to be Aspergillus niger and Aspergillus nidulans with accession numbers MZ832174 and MT919276, respectively.