聚己二酸/对苯二甲酸丁二酯塑料地膜高效降解菌群筛选及其群落结构演替特征

Screening and community succession of high effective poly(butyleneadipate-co-terephthalate) plastic mulch degrading bacteria

摘要:

【背景】以聚己二酸/对苯二甲酸丁二酯(PBAT)为主要成分的塑料地膜虽然是生物可降解的地膜，但是关于该塑料地膜降解的微生物菌群研究却较少。【目的】拟从不同环境样品中筛选可降解PBAT塑料地膜的微生物菌群。通过对其多次富集的菌群群落结构演替进行分析，明晰可降解PBAT塑料地膜的核心微生物。【方法】利用改良的SM无机盐培养基从不同环境样品中筛选可降解PBAT塑料地膜的微生物菌群；利用失重法测定菌群对PBAT塑料地膜降解的效率；利用16S rRNA基因高通量测序技术对其第五批次(G5)至第九批次(G9)富集的降解菌群的群落结构进行深入探讨；通过Pearson相关性分析方法对菌群不同菌属相对丰度变化和PBAT塑料地膜降解时间进行解析。【结果】从广州金发堆肥厂的堆肥样品中筛选到可完全降解PBAT塑料地膜的降解菌群，编号为SX。通过连续不断的转接富集，菌群SX对PBAT塑料地膜的降解速率显著提升。16S rRNA基因高通量测序结果显示第5批次(G5)至第9批次(G9)富集的PBAT塑料地膜降解菌群，厚壁菌门(Firmicutes)的相对丰度逐渐下降，而放线菌门(Actinobacteria)的相对丰度逐渐上升。硫磺色节杆菌(Arthrobacter sulfureus)、红螺菌科(Rhodospirillaceae)和噬几丁质菌科(Chitinophagaceae)在随着转接富集过程中相对丰度逐渐升高而芽孢杆菌(Bacillus sp.)的相对丰度显著降低。通过统计分析发现硫磺色节杆菌(Arthrobacter sulfureus)相对丰度升高与PBAT塑料地膜降解时间缩短显著相关(r=–0.927，p<0.05)。【结论】筛选到PBAT塑料地膜高效降解菌群SX。通过连续不断的转接富集，菌群SX对PBAT塑料地膜的降解时间由28 d (第5批次，G5)降低到13 d (第9批次，G9)。通过对菌群群落结构的研究，发现随着菌群降解效率的提高，硫磺色节杆菌的所占相对丰度显著增加，说明其可能在PBAT塑料降解中发挥着关键作用。本研究为PBAT塑料地膜的降解提供了绿色高效环保的新途径和菌株资源，并为PBAT塑料地膜降解的机制研究奠定了基础。

Abstract:

[Background] Although poly(butyleneadipate-co-terephthalate)/PBAT plastic mulch is biodegradable, little is studied on its microbial degradation. [Objective] This study was to screen bacteria from different environmental samples for degrading PBAT plastic mulch. Through the analysis of community succession structure at multiple enrichment, the core microbe group of degrading PBAT plastic mulch bacteria was studied. [Methods] The modified SM inorganic salt medium was used to screen microorganisms that can degrade PBAT plastic mulch from different environmental samples. The efficiency of microbial degradation community was determined by weight-loss method. By using 16S rRNA gene high-throughput sequencing technology, the community structure from the fifth (G5) to ninth (G9) enrichment was studied. The relative abundance of different bacterial community and the PBAT plastic mulch degradation time were analyzed by Pearson correlation analysis. [Results] The biodegradable bacterial community capable of completely degrading PBAT plastic mulch was selected from the compost samples of Guangzhou Composting Plant and named SX. Through continuous transfer and enrichment, the degradation time of PBAT plastic mulch by bacteria SX decreased from 28 days (fifth, G5) to 13 days (9th, G9), indicating that the degradation rate of PBAT plastic mulch significantly increased. The high-throughput sequencing of the 16S rRNA gene showed that the relative abundance of Firmicutes gradually decreased in the fifth (G5) to ninth (G9) of PBAT plastic mulch degrading community, and the relative abundance of Actinobacteria gradually increased. The relative abundances of Arthrobacter sulfureus, Rhodospirillaceae, and Chitinophagaceae were gradually increased, however the relative abundance of Bacillus sp. was significantly decreased. Statistical analysis revealed that the relative abundance of Arthrobacter sulfureus was significantly associated with the reduction of PBAT plastic mulch degradation time (r=–0.927, p<0.05). [Conclusion] This study provided a green, highly efficient and environmental friendly new pathway and strain resource for the degradation of PBAT plastic mulch.