Stainless steel sponge:: a novel carrier for the immobilisation of the white-rot fungus Trametes hirsuta for decolourization of textile dyes

Alginate beads.. polyurethane foam, nylon sponge and stainless steel sponge were tested as carrier materials for the white-rot fungus Trametes hirsuta for laccase production under submerged fermentation conditions. Stainless steel sponge was the best carrier material leading to the highest laccase activities of up to 800 U/l after 8 days of cultivation. These values are higher than those reported to date operating with inert supports and without inducer addition. In a 1-1 bioreactor containing T hirsuta immobilised on stainless steel sponge laccase activities of about 2200 U/l were obtained when the culture medium was supplemented with I mM copper sulphate. There were no operational problems with this system during culturing time. The textile dye Indigo Carmine was almost totally degraded in 3 days by T hirsuta grown in this bioreactor, while Lanaset Marine was degraded in two successive batches, reaching in the first batch a decolourization percentage of about 82% in 15 h and in the second one by 71% in 28 h. Results obtained after inhibition of growth of T hirsuta by antibiotics indicated that dye decolourization could not exclusively be attributed to laccase activity. (C) 2004 Elsevier Ltd. All rights reserved.