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A deacidifying/antifungal mixture composed of calcium propionate, methylparaben and propylparaben was tested against Aspergillus niger , Cladosporium cladosporioides , Chaetomium globosum , Penicillium chrysogenum and Penicillium corylophilum . The preventive treatment of paper samples resulted in a complete fungal growth inhibition on 4 of the 5 tested species. The antifungal properties of the formulation remained unaffected for a minimum period of one year. The disinfecting treatment with the mixture led to a total elimination of all tested fungal species. The effects of the tested formulation on paper were evaluated in terms of pH, colourimetry, folding endurance, FTIR and XRD, using moist heat artificial ageing. Aside from plain paper, paper previously colonized by A. niger was tested to evaluate the potential of the formulation in preventing deterioration caused by fungal metabolites. In plain paper, an effective deacidification and long-term prevention of mechanical resistance loss were achieved, although a slight paper discoloration occurred. On previously colonized by fungi, the treatment effectively prevented the deterioration caused by fungal metabolites. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]