聚乳酸/聚己二酸-对苯二甲酸丁二酯对土壤细菌群落结构的影响及其降解菌的筛选

Effects of polylactide/polybutylene adipate-co-terephthalate on bacterial community structure of soil and isolation of degrading bacteria

摘要:

【背景】近年来，聚乳酸/聚己二酸-对苯二甲酸丁二酯(polylactide/polybutylene adipate- co-terephthalate，PLA/PBAT)可降解地膜得到了广泛的使用，然而材料使用对土壤微生物的影响却鲜有报道。【目的】以新疆土壤为例，研究PLA/PBAT地膜的使用对土壤中微生物群落结构的影响；并从土壤中筛选可降解PLA/PBAT的菌株，为土壤环境的原位修复提供技术支持。【方法】采用高通量测序的方法对比使用PLA/PBAT地膜前后土壤中细菌群落的结构变化；采用筛选培养基从土壤中分离、鉴定PLA/PBAT的降解菌，通过改变不同培养条件研究菌株降解效果。【结果】使用PLA/PBAT地膜后，土壤中酸杆菌门、芽单胞菌门的相对丰度上升，变形菌门、放线菌门的相对丰度下降，这可能是地膜降解过程中其中间产物对土壤pH及微生物的抑制作用所致；并从土壤中分离出一株PLA/PBAT降解菌XJ11，初步鉴定为Delftia tsuruhatensis，在外加1.5%胰蛋白胨的PLA/PBAT (规格1 cm×1 cm×0.05 cm)筛选培养基中，接种菌液1 mL，在pH为7.2、37 °C、130 r/min的条件下，7 d内PLA/PBAT的降解率可达6.87%。【结论】PLA/PBAT地膜的使用可以改变土壤细菌群落结构，从环境中筛选出高效的PLA/PBAT降解菌成为解决地膜污染的有效措施。

Abstract:

[Background] In recent years, the polylactide/polybutylene adipate-co-terephthalate (PLA/PBAT) mulch films has been widely used. However, the effects of PLA/PBAT mulch films on bacterial community structureits has rarely been reported. [Objective] The effects of PLA/PBAT mulch films on bacterial community structure was studied. And we isolated the PLA/PBAT degrading bacteria to provide technical support for in situ remediation. [Methods] The high-throughput sequencing method was used to compare the structural changes of bacterial communities in the Xinjiang soil before and after using the PLA/PBAT mulch films. The PLA/PBAT degrading bacteria were isolated by screening medium, and the degradation effects of the strains were studied by different culture conditions. [Results] After using PLA/PBAT mulch films, the abundance of Acidophilus and Bacillus were increased, and the abundance of Proteobacteria and Actinomycetes were decreased. This might be due to the inhibitory effect of intermediate products on pH and microorganisms during the degradation process of the PLA/PBAT mulch films. Moreover, a degrading strain XJ11 was isolated from the soil, which was initially identified as Delftia tsuruhatensis. In the screening medium, 1.5% tryptone was added, 1 mL of seed solution was inoculated, the pH of the medium was adjusted to 7.2, and shaker conditions was adjusted to 37 °C and 130 r/min. The degradation rate of PLA/PBAT mulch films (specification: 1 cm×1 cm×0.05 cm) can reach 6.87%. [Conclusion] The PLA/PBAT mulch films could change the bacterial community structure of soil. Screening the PLA/PBAT degrading bacteria from the environment was an effective measure to solve the pollution of mulch films.