Poly(vinyl alcohol)–degrading enzyme

Poly(vinyl alcohol) (PVA) is widely applied in the textile industry, as a sizing agent, to increase the strength of yarn so that it can withstand high friction or to enhance the weaving process of cellulosics and their blends. To ensure the success of the bleaching process and the productions of faultless dyeing, printing, and finishing, the greige fabrics containing PVA and modified starch with other sizes must be desized. In conventional desizing method, the sized fabrics are washed with hot alkaline solution or amylase solution to eliminate the sized products, such as starch and PVA. Thus, wastewater released from such textile plant can contain large amounts of PVA and alkali. On the other hand, PVA concentration in the wastewater can be greatly decreased when PVA-degrading enzymes are used in the desizing process. Additionally, the damage to cotton fabrics caused by high temperature and harsh chemicals in the traditional desizing can be avoided in the enzyme-based desizing process. The investigation of conditions and mechanisms of microbial degradation of PVA can stimulate the screening of more strains that produce more efficient PVA-degrading enzymes to use in the desizing process. This can help reduce the environmental pollution released by the textile industry. In this chapter, the microbial degradation of PVA, the production and characteristics of PVA-degrading enzymes, and the mechanism of PVA biodegradation are reviewed.