Biodegradation of inorganic components in paper documents: Formation of calcium oxalate crystals as a consequence of Aspergillus terreus Thom growth

A sample set of model graded papers containing known organic and inorganic components was used to culture an Aspergillus terreus strain able to produce acidic metabolites and cellulolytic enzymes. This study set out to document the biogenic formation of calcium oxalate crystals, as a consequence of fungal activity and growth, on a range of paper samples. Scanning electron microscopy and FTIR spectroscopy techniques were employed to achieve this end. Bioleaching processes induced by fungi on carbonate used in the manufacture of paper, together with the capacity of fungi to produce – very rapidly – significant biogenesis of monohydrate and dihydrate calcium oxalate crystals on the surface of papers, were investigated.SEM images of calcium containing paper samples disclosed a very clear difference in the pattern of inorganic material distribution when areas spoiled by fungi and those not affected by fungal growth were compared. In addition, the FTIR spectrum of CaCO3 sized paper clearly demonstrated, following fungal growth, the FTIR absorbance of fungus and calcium oxalate, together with the disappearance of carbonate bands.