Discolouration of fungal stains on cotton textiles

Abstract

The effectiveness of an oxidative biomimetic copper-pyridine system (Cu-py-H2O2) was successfully demonstrated on model textile samples of unaged and artificially aged desized cotton inoculated with pure cultures of selected fungi, isolated from historical textile objects (Bjerkandera adusta (Basidiomycota), Cladosporium sp., Chaetomium cochlioides, Aspergillus conicus, and A. montevidensis (Ascomycota)). Colour, structure and mechanical properties of test cotton samples were evaluated. Investigation into bleaching effect against intra- and extracellular fungal pigments, and the influence on textile substrate revealed the 3-day treatment as the most appropriate length of bleaching procedure (bleaching achieved L*>90, a*<1, b*<10). The treatment had some undesirable effects on the structure and properties of the textile fabrics (cuticle flaking, longitudinal cracks, etc.), with mechanical (tensile) properties loss of maximum 60% (specific stress). The undesirable effects differed between test samples, with the least observed in control, uninoculated samples, moderate in samples, inoculated with the strains belonging to the selected ascomycetes, and the highest in the samples inoculated by selected basidiomycete (known to degrade cellulose). This is promising, as the Ascomycota are the fungi that usually cause the most intensive colouration of the textiles. Further optimization of the process may therefore lead to discolouration of the fungal stains with tolerable damage to underlaying textile.