Biological factors. Collagen, despite being essentially immune, however, it is destroyed by microorganisms. This is caused by the decomposition of substances introduced into the skin, such as tannins, fats and carbohydrates. Bacteria, yeast, fungi develop between collagen fibers, causing their decay, m.in. causing a loss of flexibility, fragility and fragility, and even shedding of fibres.
The growth of microorganisms is conditioned by the presence of a suitable substrate as a carbon source, nitrogen, inorganic compounds, but also the conditions: temperature, relative air humidity (above 70%), acidity and the presence of oxygen. Insects from the order Corodentia can feed on mold that covers moist skin, Butterflies (Lepidoptera) from the family Tineidae molars, beetles (Coleoptera) from the family Ptinidae ravishing, from the family Anobiidae. Among the fungi parasitizing on leather products, there are numerous species of the genus Aspergillus and Penicillium.
