The Role of Fungi Isolated from Historical Vegetable-Tanned Leather on the Degradation of Peptides and Amino Acids

Large numbers of leather artefacts are found in many places in Egypt such as libraries, museums, storehouses, mosques and churches. Many aspects of deterioration especially fungal stains are found on the surface of items such as bookbindings due to unfavourable environmental conditions (such as increased temperature, relative humidity, light, air pollutants etc.). This paper aims to isolate and identify fungi from vegetable-tanned leather bookbindings; study the effect of highly proteolytic fungi in the hydrolysis of leather into peptides and free amino acids, and determination of amino acid content of accelerated aged leather produced using fungi. To achieve this, we isolated and identified fungi from three historical bookbindings. Peptide nitrogen and free amino acids were estimated for up to 90 days of incubation. The effect of microbial ageing of the leather on the amino acid content was also studied. The results revealed that the most frequently found fungi were Aspergillus spp., Penicillium spp. and Alternaria spp. The enzymatic activity of these fungi towards the degradation of gelatin was much higher when a phosphate buffer was used in the media than when a citrate buffer was used. The results are expressed as clear zone (mm). Peptide and free amino acids increased during incubation times of up to 90 days. Hydrolysis plays an important role in the deterioration after infection with the studied fungi.