Transformation of high concentrations of chlorophenols by the white-rot basidiomycete Trametes versicolor immobilized on nylon mesh Mohammad
R. Sedarati Tajalli Keshavarz Alexey A. Leontievsky Christine S. Evans* *Corresponding Author
Free-cell cultures
of Trametes versicolor were compared with cultures immobilized
on nylon mesh in a 2-litre bioreactor for transformation of pentachlorophenol
(PCP) and 2,4-dichlorophenol (2,4-DCP), added at intervals to the
liquid culture medium over a period of 816 hrs. Increasing amounts
of PCP from 200 ppm to 2000 ppm added batchwise to cultures permitted
acclimatization of the fungus to these toxic pollutants. A total addition
of 2000 ppm of 2,4-DCP and 3400 ppm PCP were removed from the immobilized
cultures with 85% of 2,4-DCP and 70% of PCP transformed by enzymes
(laccase and Mn-peroxidase), 5% 2,4-DCP and 28% PCP adsorbed by the
biomass and 10% 2,4-DCP and 2% PCP retained in the medium at the termination
of the fermentation after 1020 hrs. In contrast free-cell cultures
in the same medium with the same addition regime of PCP and 2,4-DCP,
transformed 20% 2,4-DCP and 12% PCP by enzyme action, adsorbed 58%
2,4-DCP and 80% PCP by the biomass, and retained 22% 2,4-DCP and 8%
PCP in the medium. The use of nylon mesh as an immobilization matrix
for removal of PCP and 2,4-DCP facilitates more efficient removal
of chlorophenols and can be adapted to scale-up for application of
large volumes of chlorophenol-containing aqueous effluents. |
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