Enzymes have been widely used as alternatives to conventional chemicals in cleaner leather processes due to their advantages of meeting increasing environmental demands.Especially,enzymatic unhairing based on protease...Enzymes have been widely used as alternatives to conventional chemicals in cleaner leather processes due to their advantages of meeting increasing environmental demands.Especially,enzymatic unhairing based on protease has been applied to leather-making for a long time,however,it still has the key problem of slow permeation in the animal hide,resulting in slow unhairing rate,poor hair removal effect,excessive proteolysis of hide collagen,and decreased leather quality.Aiming at the key problem of bio-unhairing technology,fluorescent labeling technique and confocal laser scanning microscopy were used to investigate the protease permeation behaviors into the animal hide based on well-prepared labeled proteases,as well as the quantitative analysis of the protease amount in different hide layers.The results show that the protease mainly permeates the bovine hide through transfollicular routes from the hair side,and although the intercellular-interfibrillar pathway also exists,it does not play an important role.Additionally,the protease permeation behaviors into the hide are greatly impacted by the charge states of the hide and protease proteins,depending on the isoelectric points(pl)of the proteins and solution pH values.When the solution pH is not between the pl values of the two proteins,the similarly charged protease can quickly and deeply penetrate the hide because of the electrostatic repulsion.The established mechanism provides a theoretical basis for developing an efficient enzymatic unhairing technology for leather-making,and this can also be applied to other processes involving the enzyme permeation into the hide or leather.展开更多
[Objective] This study aimed to illustrate a protease, secreted from a newly isolated Bacillus cereus, and show its potential application in eeofriendly tannery processing. [Method] The skins, such as bovine, ovine, h...[Objective] This study aimed to illustrate a protease, secreted from a newly isolated Bacillus cereus, and show its potential application in eeofriendly tannery processing. [Method] The skins, such as bovine, ovine, hircine and porcine skins, were treated alone by the protease, which was secreted from a newly isolated Bacillus cereus, for 12 h without sulfide till the hairs were removed entirely. And then the difference of histological appearances treated with and without proteases was analyzed to reveal the dehairing mechanism. [ Result] Histological examination of skins dehaired by the crude enzymes revealed that no obvious chan- ges were observed in the dennis. Therefore it may be speculated that the proteases would firstly help in the selective breakdown of keratin tissue in the follicles viz. hydrolyzing the outer epithelial sheath of hair roots of the epidermis, provoking depilation, thereby intact hairs were pulled out without breaking other tissues of the skin. [ Conclusion] The protease produced by Bacillus cereus, strain SZ-4 could be in a great measure applied in unhairing in beamhouse of leather making exhibiting considerable unhairing capability without affecting the grain of skins as well as the tensile strength of the leather.展开更多
基金supported by National Key R&D Program of China(2017YFB0308402).
文摘Enzymes have been widely used as alternatives to conventional chemicals in cleaner leather processes due to their advantages of meeting increasing environmental demands.Especially,enzymatic unhairing based on protease has been applied to leather-making for a long time,however,it still has the key problem of slow permeation in the animal hide,resulting in slow unhairing rate,poor hair removal effect,excessive proteolysis of hide collagen,and decreased leather quality.Aiming at the key problem of bio-unhairing technology,fluorescent labeling technique and confocal laser scanning microscopy were used to investigate the protease permeation behaviors into the animal hide based on well-prepared labeled proteases,as well as the quantitative analysis of the protease amount in different hide layers.The results show that the protease mainly permeates the bovine hide through transfollicular routes from the hair side,and although the intercellular-interfibrillar pathway also exists,it does not play an important role.Additionally,the protease permeation behaviors into the hide are greatly impacted by the charge states of the hide and protease proteins,depending on the isoelectric points(pl)of the proteins and solution pH values.When the solution pH is not between the pl values of the two proteins,the similarly charged protease can quickly and deeply penetrate the hide because of the electrostatic repulsion.The established mechanism provides a theoretical basis for developing an efficient enzymatic unhairing technology for leather-making,and this can also be applied to other processes involving the enzyme permeation into the hide or leather.
基金Supported by the Team of Innovation of Science and Technology on Utilization of Solid Waste,Guizhou Province[(2010)4011]the Key Program of National Natural Science Found of FoundationChina(20536030)
文摘[Objective] This study aimed to illustrate a protease, secreted from a newly isolated Bacillus cereus, and show its potential application in eeofriendly tannery processing. [Method] The skins, such as bovine, ovine, hircine and porcine skins, were treated alone by the protease, which was secreted from a newly isolated Bacillus cereus, for 12 h without sulfide till the hairs were removed entirely. And then the difference of histological appearances treated with and without proteases was analyzed to reveal the dehairing mechanism. [ Result] Histological examination of skins dehaired by the crude enzymes revealed that no obvious chan- ges were observed in the dennis. Therefore it may be speculated that the proteases would firstly help in the selective breakdown of keratin tissue in the follicles viz. hydrolyzing the outer epithelial sheath of hair roots of the epidermis, provoking depilation, thereby intact hairs were pulled out without breaking other tissues of the skin. [ Conclusion] The protease produced by Bacillus cereus, strain SZ-4 could be in a great measure applied in unhairing in beamhouse of leather making exhibiting considerable unhairing capability without affecting the grain of skins as well as the tensile strength of the leather.
