Study of Cellulosic Fiber Degradation by Four Common Fungi : Chromatic Alterations and SEM Examination

In the present study, papers manufactured from cotton cellulose were used. White paper (without inks), paper with cinnabar ink (red ink and HgS), and paper with iron gall ink (black) were used to facilitate colonization by Trichoderma viride, Penicillium roqueforti, Eurotium chevalievi, and Aspergillus flavus. The identification of cellulose, and the inks used and binder material (Arabic gum) was achieved using FTIR spectra. Degradation of cellulosic fiber was performed by measuring the hyphal growth of the studied fungi using an environmental scanning electron microscope (ESEM). Color changes in the inoculated papers with each of the four fungi tested was determined by assessing the surface of the studied cellulosic fibers treated with tea tree oil (0.25%) and thyme oil (0.5%). The color change values (ΔE) refer to fungal growth. The least fungal growth (A. flavus) was found on the white and red papers treated with tea tree oil, with a ΔE value of 1.95, whereas the highest fungal growth (ΔE 39.17) was exhibited by T. viride on red paper treated with thyme oil. The greater value of ΔE between the control and inoculated samples of the same species in the same type of paper presented the highest fungal growth on the paper. From both the ESEM examination and the chromatic alteration of the inoculated papers with four fungi, T. viride was observed to be the most destructive fungus for the tested papers, whereas A. flavus was the least destructive.