Abstract: The aim of this work is to isolate and identify the strains which can effectively degrade polyvinyl alcohol（PVA）from the composting degradation process of PVA foams and further to study the degradation effects and characteristics of these strains on PVA. First,the PVA foam was degraded after 3 years composting,and we used Fourier Transform Infrared Spectroscopy（FTIR）to detect the molecular structure change of the foam. Then we used Finley method to screen the strains with better degradability from the degraded foams. Further we combined morphological characteristics,gram staining experiment and 16s rRNA gene sequence alignment to identify the strains. Finally we employed UV ultraviolet spectrophotometer to measure the degradation rates of PVA by various strains and the OD₆₀₀ of cells in shake flask,and we also compared the degradability of PVA by the screened strains at 2 alcoholysis degrees. The results showed new carboxyl groups and hydroxyl groups appeared in the molecular structure of the PVA foam after 3 years composting degradation;4 strains were screened and identified,including Bacillus sp. DG01,Bacillus sp. DG02,Paenibacillus sp. DG03 and Paenibacillus sp. DG04. The degradation rates by these 4 isolated strains at 3.0 g/L PVA1788 were 67.27%,74.99%,56.74% and 59.70%,respectively,and the degradation rates at 3.0 g/L PVA1799 were 58.27%,54.47%,43.32%,and 46.59%,respectively. The PVA foams presented obvious group changes after the composting;the growth of 4 strains was coupled with the degradation of PVA,and the low alcoholysis degree of PVA was more beneficial to the biodegradation.

Key words: polyvinyl alcohol, screen, biodegradation, FTIR, alcoholysis degree