A new polyvinyl alcohol (PVA)-degrading bacterium was isolated from activated sludge sampled during a waste water treatment process and identified as Sphingomonas sp. Its PVA oxidase activity and alcohol dehydrogenase activity for various low-molecular-weight secondary alcohols were detected. Both activities were associated with cells of the degrader, and they were not extracellular. Under optimal conditions, the isolate was able to degrade 500 mg of PVA per litre in 2 weeks. The strain required pyrroloquinoline quinone (PQQ) and another growth factor, the later could be supplied by a co-isolated Rhodococcus erythropolis strain. The findings stressed the complex nature of environmental PVA degradation and proved that other factors different from PQQ could be important in symbiotic biodegradation of PVA with some sphingomonads.