Abstract：
Plastic pollution has become a major environmental concern globally, and novel and eco-friendly approaches like bioremediation are essential to mitigate the impact. Low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and expanded polystyrene (EPS) are three of the most frequently used plastic types. This study examined biodegradation of these using Zophobas atratus larvae, followed by isolation and whole genome sequencing of gut bacteria collected from larvae frass. Over 36 days, 24.04 % LDPE, 20.01 % EPS, and 15.12 % LLDPE were consumed on average by the larvae, with survival rates of 85 %, 90 %, and 87 %, respectively. Fourier transform infrared spectroscopy (FTIR) analysis of fresh plastic types, consumed plastics, and larvae frass showed proof of plastic oxidation in the gut. Frass bacteria were isolated and cultured in minimal salt media supplemented with plastics as the sole carbon source. Two isolates of bacteria were sampled from these cultures, designated PDB-1 and PDB-2. PDB-1 could survive on LDPE and LLDPE as carbon sources, whereas PDB-2 could survive on EPS. Scanning Electron Microscopy (SEM) provided proof of degradation in both cases. Both isolates were identified as strains of Pseudomonas aeruginosa, followed by sequencing, assembly, and annotation of their genomes. LDPE- and LLDPE-degrading enzymes e.g., P450 monooxygenase, alkane monooxygenase, alcohol dehydrogenase, etc. were identified in PDB-1. Similarly, phenylacetaldehyde dehydrogenase and other enzymes involved in EPS degradation were identified in PDB-2. Genes of both isolates were compared with genomes of known plastic-degrading P. aeruginosa strains. Virulence factors, antibiotic-resistance genes, and rhamnolipid biosurfactant biosynthesis genes were also identified in both isolates. This study indicated Zophobas atratus larvae as potential LDPE, LLDPE, and EPS biodegradation agent. Additionally, the isolated strains of Pseudomonas aeruginosa provide a more direct and eco-friendly solution for plastic degradation. Confirmation and modification of the plastic-degrading pathways in the bacteria may create scope for metabolic engineering in the future.
摘要：
塑料污染已成为全球主要的环境问题，生物修复等新型环保方法对于减轻影响至关重要。低密度聚乙烯（LDPE），线性低密度聚乙烯（LLDPE），和发泡聚苯乙烯（EPS）是三种最常用的塑料类型。这项研究使用Zophobasatratus幼虫检查了这些的生物降解，然后对从幼虫中收集的肠道细菌进行分离和全基因组测序。超过36天,24.04%LDPE，每股收益20.01%，幼虫平均消耗15.12%的LLDPE，存活率为85%,90%,87%,分别。傅里叶变换红外光谱(FTIR)分析新鲜塑料类型,消耗的塑料，幼虫Frass在肠道中显示出塑料氧化的证据。在补充有塑料作为唯一碳源的基本盐培养基中分离并培养Frass细菌。从这些培养物中取样了两种细菌，指定为PDB-1和PDB-2。PDB-1可以在LDPE和LLDPE上作为碳源存活，而PDB-2可以在EPS上存活。扫描电子显微镜（SEM）提供了两种情况下降解的证据。两株分离物均被鉴定为铜绿假单胞菌，其次是测序，装配,和它们基因组的注释。LDPE和LLDPE降解酶，例如P450单加氧酶,烷烃单加氧酶，乙醇脱氢酶,等。在PDB-1中鉴定。同样，在PDB-2中鉴定了苯乙醛脱氢酶和其他参与EPS降解的酶。将两种分离物的基因与已知的塑料降解铜绿假单胞菌菌株的基因组进行比较。毒力因子,抗生素抗性基因，和鼠李糖脂生物表面活性剂生物合成基因也在两个分离物中被鉴定。本研究表明Zophobasatratus幼虫是潜在的LDPE，LLDPE,和EPS生物降解剂。此外,铜绿假单胞菌的分离菌株为塑料降解提供了更直接、更环保的解决方案。细菌中塑料降解途径的确认和修饰可能为将来的代谢工程创造空间。
