Enzyme cotton fiber, effect

An important chemical finishing process for cotton fabrics is that of mercerization, which improves strength, luster, and dye receptivity. Mercerization iavolves brief exposure of the fabric under tension to concentrated (20—25 wt %) NaOH solution (14). In this treatment, the cotton fibers become more circular ia cross-section and smoother ia surface appearance, which iacreases their luster. At the molecular level, mercerization causes a decrease ia the degree of crystallinity and a transformation of the cellulose crystal form. These fine stmctural changes iacrease the moisture and dye absorption properties of the fiber. Biopolishing is a relatively new treatment of cotton fabrics, involving ceUulase enzymes, to produce special surface effects (15). 

Figure 9. Effect of enzyme components from T. koningii cellulose on the formation of alkali-soluble cellulose from cotton fiber. A reaction mixture consisting of 200 mg of cotton, 2 mL of 0.2 M acetate buffer, pH 4.5, enzyme, water, and NaNs solution to give a total volume of 10 mL, was incubated at 50°C for various times. Percentage hydrolysis was calculated from the loss in weight determined on weighed crucibles. The fraction soluble in alkali (10% NaOH) was determined in a similar fashion after incubating for 3 hr at 25°C. Ct ( - 0) Cx + /3-glucosidase ( - ) ...

The effect of microorganisms results in noticeable changes in chemical composition and physical stracture of cotton fibers. As found by electron microscopy, cotton fiber degradation by enzymes is most intensive in the zones of lower fibril stracmre density [24],... 

An important parameter influencing the mode of action of cellulases is the accessibility of the cellulose to the enzymes. The molecular weights of cellulases range between 30 and 80 kDa. A comparison of the size of cellulase (3-8 nm) and the pore size of cotton swollen in water (1-7 nm) shows very clearly that cellulases can penetrate the cellulose to a limited extent only. In addition, the enzyme reaction takes place preferentially on amorphous cellulose because the more compact, crystalline cellulose structures do not offer any space for such macromolecules. Thus - provided of enzyme and process parameters have been selected correctly -cellulases act mainly on the textile surface. In this way interesting effects on cellu-losic fibers can be achieved. 

The potential to use bioactive fibers with selective mzymatic propaties through grafting or covalent attachment of the enzyme on the surfece of fibrous materials has been attempted. Immobilization of alpha-amylase (61) and glucose oxidase (62) have been reported on a variety of fiibrics. Edwards et al. (63) have recmtly cempared the antimicrobial activity of glycine-linked lysozyme on cotton cellulose fabrics (Fig. 7). The aizyme-cellulose conjugates were shown be more effective in the lysis of gram-positive bacteria than freely soluble lysozyme. 

Tsatsaroni, E. Liakopoulou-Kyriakides, M. Effect of enzymic treatment on the dyeing of cotton and wool fibers with natural dyes. Dyes Pigm. 1995, 29, 203-209. 

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