Mycelial growth and enzymatic activities of fungi isolated from recycled paper wastes grown on Di (2-ethylhexyl) phthalate

Abstract

Phthalate esters are often discharged into the ecosystem by paper and plastic industries during manufacturing processes, contributing to environmental pollution. Di (2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics that imparts flexibility to polyvinyl chloride resins. This is an endocrine-disrupting compound that could lead to cancer. Filamentous fungi were isolated from mixed pulp waste in a paper recycling facility. Ribosomal DNA internal transcribed spacers sequencing were performed, which allowed for the identification of the fungal species of the isolates as Neurospora sitophila, Fusarium culmorum, Trichoderma atroviride, Hypocrea lixii, and Trichoderma harzianum. Radial growth rate (ur), mycelial biomass, and laccase and esterase activities of the fungal isolates in media containing different concentrations of DEHP (0, 500, 750, 1,000, 1,200, and 1,500 mg/l) were carried out. The highest ur was shown by N. sitophila in the medium added with 1,500 mg of DEHP/l. The largest mycelial biomass was produced by F. culmorum, T. atroviride, H. lixii, and T. harzianum in the medium containing 1,500 mg of DEHP/l. F. culmorum and T. harzianum had higher esterase activity than laccase activity in all the media tested. This study demonstrates that fungi isolated from the recycled paper wastes in a paper industry were capable of utilizing DEHP as the sole carbon source. These fungal isolates can be used for the bioremediation of DEHP-contaminated sites.