Mucormycosis is a common name of filamentous fungi, which means "mouldy fungi", usually refers to the mycelium developed and does not have large fruiting bodies of fungi.They are often in a humid climate grow, grow visible filamentous, fleece or cobweb mycelium, good land natural disposition, under natural conditions, often causing food, agricultural and industrial products of mildew and plant fungus disease.Mold in the leather on the growth has the following 3 reasons.
First, leather containing mold growth nutrient source.As everyone knows, leather is a natural macromolecular compound processing products, the main ingredient is collagen protein and fat, in leather processing also added a number of animal and vegetable fats and oils, salts and minerals, as well as casein and other substances, these are the mold growth is needed for good nutrition source.
In second, large airborne mold spores in the presence of.The fungal spores in gone with the wind, reconcile oneself to one's situation, once they fall into the leather, because you can get rich in nutrition, easy to growth and reproduction.
Third, leather processing and storage conditions, conducive to mold growth and reproduction.
Mold growth temperature, humidity and pH range is very wide, suitable growth temperature is 25~35 ℃, relative humidity is higher than 75%, pH value between 1.5~11 in general, optimum pH value is about 0 6?.In the tanning process, such as pickling, tanning, retanning and finishing, leather and leather in acidic conditions, and leather, porous structure hygroscopicity strong, its high water content (leather moisture content in general 14%~18%), therefore, in our country south the climate is hot, air humidity conditions, leather and its products is extremely easy to mold, in the north also have mildew may.To wet blue leather and leather products, storage and transportation process in hot and humid environment, but also for the leather mildew provided favorable conditions.Usually, mold in leather processing the following phases of growth: ①pickling chrome tanning wet blue leather; ②; ③dyeing leather; ④vegetable-tanned billet; ⑤vegetable tanning liquid; the finished leather.
According to mildew mechanism, the mold to the leather inside some nutrients, such as carbohydrates, protein, fat and other organic compounds, and secrete corresponding enzymes, such as amylase, cellulase, enzyme to skim, larger molecular substances decomposed into soluble small molecules, such as glucose, amino acids,: through the cell membrane absorption, transfer, and after a series of anabolic, into their desired life substances.Then, the leather of nutrient substance in constantly is decomposed at the same time, mold growing breed, with mold quantity increases, further accelerated the leather mildew.
At the same time, mold growth in decomposition of nutrients and generate "waste", or metabolic activity in the secretory product, such as pigment, is likely to produce more leather invasion, or destructive effect the quality of leather.Finally, in the mold to multiply, due to cell aggregation and accumulation, formation of the foreign body may cause fiber gap channel blockage.Specifically, the mold to the quality of leather in the main effects of leather pigment deposition, which stains; ②dyeing, finishing the inhomogeneity of oil; the frost formation; ④pickling hide some of the molds to leather fiber degradation effect; ⑤on leather physical and mechanical properties, especially strength damage.
In general, the surface of leather mild mildew lawn can wipe, affecting only the appearance of the leather, leather grain surface loses luster; and serious mildew may make the leather grain mildew, intestinal crack, not only affects the appearance of leather, leather and significantly reduce the physical and mechanical properties of leather, seriously affected the sale and use of performance.
The species of mildew on leather, with leather types and the different climate and environment conditions are different.At home, Ma Zhenying reports, Shanghai leather mildew is by Aspergillus flavus, Hijima,, nettle Penicillium, Penicillium chrysogenum, Penicillium funiculosum Penicillium citrinum,, Paecilomyces, Trichoderma, Mucor Rhizopus, mainly caused by; Hunan, Jiangxi, Guangzhou, in order to Aspergillus flavus, Aspergillus fumigatus, Penicillium citrinum, arc paste mycophenolate, Rhizopus and Mucor dominant; and Sichuan to Aspergillus versicolor, Aspergillus clavatus, white, Aspergillus, Penicillium decumbens, Wright Penicillium, Paecilomyces, Alternaria, Trichoderma, Fusarium and other more common.Lu Xuyong [14] in Shanghai and Chengdu sampling analysis, 11 kinds of molds, respectively: Aspergillus niger, Aspergillus versicolor, Aspergillus fumigatus, west of Aspergillus fumigatus, ball Chaetomium, wax leaf Thamnidium, powder falling mycophenolate, Aspergillus glaucus, Aspergillus flavus, Aspergillus nidulans and actinomycetes.
Liu Yan and other purification from Guangdong mouldy wet blue leather, have respectively: Aspergillus, Penicillium, Aspergillus, Trichoderma, powder mildew and scab fungus colony.In foreign countries, Japan's Sang Tianfu reports, pollution leather mold is mainly from Penicillium citrinum, spines, hooded Penicillium, Aspergillus, Penicillium purpurogenum white rust, Aspergillus chevalieri, Aspergillus, Alternaria, Acremonium SP, Cladosporium, short Scopulariopsis brevicaulis, while in Poland, separated from the a variety of wood mold, Penicillium, Aspergillus, Fusarium, Rhizopus and Torulopsis etc..In the vegetable tanned leather, leather to long-term immersion bath fungus were found to be statistically: Penicillium bacteria accounted for 60%, Aspergillus fungus occupies 17%, Paecilomyces bacteria accounted for 12%, Rhizopus bacteria accounted for 6%, the genus Trichoderma bacteria accounted for 4%.In addition, from the fatliquoring agent and synthetic leather, also isolated from Penicillium, Aspergillus, Fusarium, Alternaria, Trichoderma, ball Chaetomium, Rhizopus and Absidia corymbifera etc..