Biodegradation of polyvinyl alcohol by a mixed microbial culture

A mixed culture capable of degrading 1 g l−1 polyvinyl alcohol (PVA) completely was screened from sludge samples at Pacific Textile Factory, Wuxi, China. This mixed culture had stronger capability of degrading PVA with low polymerization and high saponification than degrading PVA with high polymerization and low saponification. Inorganic nitrogen source was more suitable for the mixed culture to grow and degrade PVA than organic nitrogen source. Microorganisms and relative abundance of this mixed culture were explored by terminal restriction fragment length polymorphism (T-RFLP). Small PVA molecules were detected in cell extracts of the mixed culture. This indicated that PVA degradation in the mixed culture was in fact a combined action of extracellular and intracellular enzymes. Two strains producing extracellular PVA-degrading enzyme were isolated from the mixed culture. They could individually degrade PVA1799 with polymerization of 1700 from initial average molecular weight 112,981 to 98,827 Da and 84,803 Da, respectively. However, only small amount of PVA124 in polymerization of 400 could be degraded by these two strains.