Deterioration of contemporary and artificially aged cotton by selected fungal species

The scope of this study was an analysis of the deterioration of cotton fibres caused by selected strains of fungal species from historical cotton textile objects. Aged and non-aged cotton fabric specimens were inoculated with representative strains of the six highest frequency fungal species isolated from museum textile objects from different Slovene museums. The selected fungi were Aspergillus clavatus, Cladosporium cladosporoides, Fomes fomentarius, Hypoxylon fragiforme, Penicillium chrysogenum and Penicillium corylophilum. Their effects on contemporary and artificially aged cotton was examined by Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, and tensile behaviour. These fungal species affected the cellulose structure and fabric properties differently. Among the fungi analysed, P. chrysogenum was least harmful to cotton-cellulose samples, while C. cladosporoides, F. fomentarius and H. fragiforme showed the greatest effects. The main structural changes were hydrolysis, depolymerisation, and decreased molecular order. Although not all of these fungal species are dangerous to cotton fibres, and hence to museum objects, they all cause visible changes that can lead to disintegration of these objects. Another important factor that accelerates the depolymerisation of cellulose macromolecules in cotton fibre is inappropriate storage conditions, which should be avoided at all costs, to preserve historical objects and artefacts.