Biosorption of organochlorine pesticides using fungal biomass

Cladosporium strain AJR³18,501 was tested for its ability to sorb the organochlorine pesticide (OCP) p,p′-DDT from aqueous media. When p,p′-DDT was added to distilled water, ethanol or 1-propanol solutions in excess of its solubility, p,p′-DDT was sorbed onto the fungal biomass. Increasing the amount of p,p′-DDT in solution by changing the medium composition increased sorbent uptake: p,p′-DDT uptake by the fungal biomass was 2.5 times greater in 25% 1-propanol (17 mg of p,p′-DDT g⁻¹ dry weight fungal biomass) than in distilled water. When p,p′-DDT was dissolved in 25% 1-propanol (12 mg l⁻¹), rapid p,p′-DDT sorption occurred during the first 60 min of incubation. p,p′-DDT in solution was reduced to 2.5 mg l⁻¹ with the remaining p,p′-DDT recovered from the fungal biomass. A number of environmental parameters were tested to determine their effect on p,p′-DDT biosorption. As arsenic (As) is prevalent at DDT-contaminated cattle dip sites, its effect on p,p′-DDT uptake was determined. The presence of As As(III) or As(V) up to 50 mg l⁻¹] did not inhibit p,p′-DDT uptake and neither As species could be sorbed by the fungal biomass. Changing the pH of the medium from pH 3 to 10 had a small effect on p,p′-DDT sorption at low pH indicating that an ion exchange process is not the major mechanism for p,p′-DDT sorption. Other mechanisms such as Van der Waals forces, chemical binding, hydrogen bonding or ligand exchange may be involved in p,p′-DDT uptake by Cladosporium strain AJR³18,501. Journal of Industrial Microbiology & Biotechnology (2002) 29, 163–169 doi:10.1038/sj.jim.7000280 Received 15 January 2002/ Accepted in revised form 18 May 2002