Enzyme enhanced bleaching and depigmentation of wool and specialty animal fibres

This paper deals with the use of enzymes as a tool for reducing the environmental impact of strong oxidative processes of the textile industry, such as bleaching and depigmentation of animal hair. “Bio-bleaching” of wool tops, previously subjected to shrink resistant treatments, and bio-depigmentation of cashmere and dark camel fibre samples, were carried out on a laboratory scale. Unlike conventional oxidative treatments, proteolytic enzymes were added into the process liquors, with the purpose of improving the degree of whiteness or reducing the damage to the fibres. The specific action of these enzymes is to hydrolyse the peptide bonds of the proteins, making the fibre more susceptible to penetration of the oxidizing agent (1,2). Subsequently to the laboratory trials, the enzyme-enhanced bleaching of Basolan-treated wool tops was scaled up, in an industrial wool plant. A general improvement of the properties of the fibres was found to be associated to these environmentally friendly bio-technological processes

Interaction of Subtilisin-type Protease with Merino Wool Fibres

In order to understand the structural modifications caused by proteolytic enzymes on wool fibers, the interaction of subtilisin-type protease with Merino wool was studied by physical and physico-chemical techniques. Enhanced wool dye affinity and optical microscopy examination indicate increasing fiber damage as a function of enzyme action. Scanning electron microscopy suggests a preferential proteolytic attack on the Cellular Membrane Complex (CMC), a non-cellular and non-keratinic material, while no significant degradation of cortical and cuticular cells was observed. SDS-PAGE (after fiber dissolution in urea) shows progressive proteolysis of low-sulfur containing proteins, which are considered to be part of non-keratinic structures. High ionic strength in the incubation medium provides protection of the fiber interior, by limiting proteolysis to the epicuticule. FTIR-ATR indicates that no change in the redox state of -S-S- cystine bonds takes place, which occurs with currently used oxidative treatments (e.g., Basolan DC). Accordingly, wool top treated with an oxidatively stable serine protease acquires minimal non-felting properties, as proven by the Aachen felting test, even in the presence of hydrogen peroxide. It is concluded that commercially available subtilisin-type proteases are useful tools in the study of wool / enzyme interactions and can be used to enhance hand feel or lustre of wool articles, but might be of limited use in shrink-resistance treatments

Synthesis and anti-bacterial activity of a library of 1,2-benzisothiazol-3(2H)-one (BIT) derivatives amenable of crosslinking to polysaccharides

1,2-Benzisothiazol-3(2H)-one (BIT) is one of the most common chemical biocides in industrial products, with a heterocyclic structure and a wide range of antimicrobial activity. A library of BIT derivatives was synthesized and characterized, from which 18 compounds were selected, tested for anti-bacterial activity relative to the parent molecule and amenable of coupling to plant polysaccharides in general and to galactomannans (GM) in particular, widely used as rheology modifiers, but with limited \u201cbiostability\u201d. Four sites on the BIT core were targeted: the nitrogen and the oxygen atoms on the heterocyclic ring, the C5 and the C6 positions on the aromatic ring, where functional groups were introduced. The ultimate aim of this work is to establish whether by covalently linking a biocide to GM polymers, their \u201cbiostability\u201d can be improved

Aerogels of enzymatically oxidized galactomannans from leguminous plants: Versatile delivery systems of antimicrobial peptides and enzymes

We describe aerogels obtained by laccase/TEMPO-oxidation and lyophilization of galactomannans (GM) from fenugreek, sesbania and guar. Enzymatic oxidation of GM in aqueous solution caused viscosity increase up to fifteen-fold, generating structured, elastic, stable hydrogels, presumably due to establishment of hemiacetalic bonds between newly formed carbonyl groups and free hydroxyl groups. Upon lyophilization, water-insoluble aerogels were obtained, whose mechanical properties and porosity were investigated. Active principles were absorbed into the aerogels from aqueous solutions and, following rinsing, blotting, re-lyophilization, were released in an appropriate medium. The release of the antibiotic polymyxin B was tested against six different Gram-negative bacterial strains, of the antimicrobial peptide nisin against two Gram-positive and of the muraminidase lysozyme against one anaerobic strain. Protease and lipase release in solution from \u201cenzyme loaded\u201d aerogels was monitored by the increase in enzymatic activity. These biomaterials could represent new versatile, biocompatible \u201cdelivery systems\u201d of actives for biomedical and industrial applications