聚乙烯醇降解细菌筛选及其降解特性

Identification and Characterization of Bacteria Degrading Polyvinyl Alcohol

从聚乙烯醇泡棉的堆肥降解过程中筛选出可以有效降解聚乙烯醇的菌株,并研究其对聚乙烯醇的降解效果和降解特性。将聚乙烯醇泡棉经过3 年的堆肥降解,利用傅里叶转换红外光谱(Fourier transform infrared spectroscopy,FTIR)检测泡棉的分子结构变化;采用Finley 法从降解后的聚乙烯醇泡棉中筛选降解效果较好的菌株,通过菌落形态和细胞染色以及16S rRNA 基因序列比对进行鉴定;通过紫外分光光度计检测菌株在降解聚乙烯醇材料过程中的菌体浓度变化和聚乙烯醇降解程度,并将筛选菌株对两种醇解度的聚乙烯醇降解效果进行对比。结果表明,经过3 年的堆肥降解,聚乙烯醇泡棉分子结构中出现了新的羧基和羟基;筛选得到了四株菌,即Bacillus sp.DG01、Bacillus sp.DG02、Paenibacillus sp.DG03、Paenibacillus sp.DG04。这4 株筛选菌株对3.0g/L PVA1788 的降解率分别为67.27%、74.99%、56.74%和59.70%,对3.0 g/L PVA1799 的降解率分别为58.27%、54.47%、43.32%和46.59%。PVA 泡棉在堆肥降解过程中发生了明显的基团变化,4 株菌的生长与聚乙烯醇的降解过程呈耦联关系,且4 株菌株整体上对较低醇解度的PVA 降解效果更好。

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.