Industrial and Environmental Sustainability Laboratory, Department of Biotechnology, School of Bioengineering, SRM Institute of science and technology, Kattankulathur-603203, Chengalpattu District, Tamil Nadu, India.
Industrial and Environmental Sustainability Laboratory, Department of Biotechnology, School of Bioengineering, SRM Institute of science and technology, Kattankulathur-603203, Chengalpattu District, Tamil Nadu, India.
Sci Total Environ. 2023 Dec 15;904:166721. doi: 10.1016/j.scitotenv.2023.166721. Epub 2023 Sep 4.
Plastic pollution is a major global environmental issue due to its structural complexity and poor biodegradability. Biological approaches are appropriate due to cost effectiveness and environmental friendliness, however effective polymer degradation is still in its infancy. As biological treatments are slower than physical and chemical approaches, they could be applied in conjunction with pre-treatment techniques such as photo-oxidation, heat treatment, and chemical treatments. But these processes lead to high energy consumption and hazardous secondary pollution. To address these concerns, an enzymatic pre-treatment strategy has been proposed in this study, with an aim of promoting surface oxidation on the plastics leading to improved hydrophilicity. This in turn, facilitates the surface attachment of microbes, ultimately, accelerating biodegradation. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy analyses confirmed the surface oxidation of the polyethylene (PE) and polycarbonate (PC) plastics mediated by the action of laccase enzyme. Contact angle measurement witnessed the increased hydrophilicity of the treated plastics. Following, a potential biofilm forming microbial consortium has been employed for the biodegradation of enzyme treated plastics. SEM analysis indicated the increased formation of corrosive pits and surface aberrations on the enzymatically pre-treated plastics and Confocal Laser Scanning microscopy (CLSM) analysis exhibited the enhanced biofilm formation and exopolysaccharide deposition on the pre-treated PE and PC. In addition, X-ray photoelectron spectroscopy (XPS) revealed the reduction in the elemental composition of carbon with an increment in the oxygen composition of plastics. Gel permeation chromatography (GPC) further confirmed the greater reduction in the molecular weights of the plastics subjected to integrated enzymatic and biofilm treatment than only biofilm treated plastics. This is the first report on the integration of enzymatic pre-treatment with the biofilm mediated microbial degradation to achieve enhanced treatment of plastics which demonstrated to be a promising technology for the effective mitigation of plastic pollution.
塑料污染是一个全球性的重大环境问题，其结构复杂，生物降解性差。由于成本效益和环境友好性，生物方法是合适的，然而有效的聚合物降解仍处于起步阶段。由于生物处理比物理和化学方法慢，它们可以与预处理技术结合使用，如光氧化、热处理和化学处理。但这些过程会导致高能耗和危险的二次污染。针对这些问题，本研究提出了一种酶预处理策略，旨在促进塑料表面氧化，提高其亲水性。这反过来又促进了微生物在表面的附着，最终加速了生物降解。扫描电子显微镜（SEM）和傅里叶变换红外（FT-IR）光谱分析证实了漆酶酶介导的聚乙烯（PE）和聚碳酸酯（PC）塑料的表面氧化。接触角测量见证了处理后塑料亲水性的增加。随后，采用潜在的生物膜形成微生物群落对酶处理后的塑料进行生物降解。SEM 分析表明，酶预处理后的塑料表面腐蚀性凹坑和表面不规则性的形成增加，共焦激光扫描显微镜（CLSM）分析显示，酶预处理后的 PE 和 PC 上生物膜的形成和胞外多糖的沉积增强。此外，X 射线光电子能谱（XPS）显示，随着塑料中碳元素组成的减少和氧元素组成的增加。凝胶渗透色谱（GPC）进一步证实，与仅经生物膜处理的塑料相比，经综合酶和生物膜处理的塑料的分子量降低更大。这是首次报道将酶预处理与生物膜介导的微生物降解相结合，以实现增强塑料处理的效果，这证明是一种有效的减轻塑料污染的有前途的技术。
