Abstract：
Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film\'s surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.
摘要：
低密度聚乙烯（LDPE）由于其高产量和对环境的顽抗性而导致大量的环境积累。在这项研究中,我们成功地富集和分离了两个菌株，硝酸盐还原剂sp.Z-1和Gordoniasp.Z-2，来自能够降解LDPE膜的沿海塑料碎片。在30℃下孵育30天后，菌株Z-1和Z-2分别使支链LDPE（BLDPE）膜的重量降低了2.59％和10.27％。此外，高温凝胶渗透色谱(HT-GPC)分析显示BLDPE膜中的分子量降低7.69%(Z-1)和23.22%(Z-2)。扫描电子显微镜（SEM）图像显示膜表面上存在微生物定植和穿孔。傅里叶变换红外光谱(FTIR)分析显示新的官能团,例如LDPE薄膜中的羰基和碳-碳双键。在LDPE降解过程中，两种菌株均产生细胞外活性氧（ROS）。GC-MS分析显示降解产物包括短链烷烃，链烷醇,脂肪酸，和酯类。基因组分析确定了许多可能参与LDPE断链的胞外酶。提出了一个模型，表明ROS和胞外酶在LDPE的生物降解中具有协同作用。这表明菌株Z-1和Z-2可以降解LDPE，为深入研究生物降解机理提供了依据。
