The current study is interested in evaluating the decay of cotton, Whatman and chemical pulp caused by Trichoderma harzianum and Paecilomyces variotii. The structural changes of the paper were evaluated by Infrared Spectroscopy (FTIR) and
Scanning Electron Microscope (SEM). The SEM results show differences in hyphae colonization and paper decay patterns
between studied species under the current study; P. variotii caused an eroded structure in the cotton (cavity forming), whereas
the initial T. harzianum colonization produced rupture and erosion (soft-rot decay type II) for the three types of paper ,the
gaps were elongated with sharp pointed ends, which consisted either of individual cavities or in chains. Moreover, FTIR
results confirmed that there a relationship could be observed between fungal decay and crystalline cellulose content because
the intensity of peaks at 1335 and 1111 cm−1 significantly decreased due to the fungal decay. Furthermore, the intensity of
O–H stretching absorption slightly decreased, and this may be attributed to hydrolysis of cellulose molecules.

• A Microscopic Study of Paper Decayed by Trichoderma harzianum and Paecilomyces variotii