Bai Fuliang, Fan Jie, Zhang Xiangyu, Wang Xuemeng, Liu Shuo
School of Geographical Science, Harbin Normal University, Harbin 150025, China.
School of Geographical Science, Harbin Normal University, Harbin 150025, China.
J Hazard Mater. 2025 May 5;488:137330. doi: 10.1016/j.jhazmat.2025.137330. Epub 2025 Jan 22.
Microplastics (MPs) pose an emerging threat to vegetable growing soils in Harbin, which have a relatively high abundance (11,065 n/kg) with 17.26 of potential ecological risk of single polymer hazard (EI) and 33.92 of potential ecological risk index (PERI). Polyethylene (PE) is the main type of microplastic pollution in vegetable growing soils in Harbin. In this study, the engineered Bacillus velezensis with polyethylene-group-degrading enzyme pathway (BCAv-PEase) was constructed to enhance the degradation of MPs of PE (PE-MPs). BCAv-PEase increased the biodegradation of PE-MPs, promoted weight loss of PE films, elevated surface tension, and decreased the surface hydrophobicity of PE through upregulating activities of depolymerases, dehydrogenase, and catalase. Mechanism analysis showed that BCAv-PEase degraded PE-MPs by promoting the secretion of PEase, thereby leading to the generation of new oxygenated functional groups within the PE-MPs substrate, which further accelerated the metabolic pathway of PE-MPs. The analysis of the microbial community during the PE-MPs degradation processes revealed that BCAv-PEase emerged as the principal bacterial player and stimulated the abundance of microbes and functional genes associated with the biodegradation of PE. In conclusion, this study provides a potential mechanism for biodegradation of PE-MPs mediated by BCAv-PEase via modulating substrate selectivity and optimizing biocatalytic pathways.
微塑料（MPs）对哈尔滨的蔬菜种植土壤构成了新出现的威胁，这些土壤中微塑料含量相对较高（11,065 n/kg），单一聚合物危害的潜在生态风险（EI）为17.26，潜在生态风险指数（PERI）为33.92。聚乙烯（PE）是哈尔滨蔬菜种植土壤中微塑料污染的主要类型。在本研究中，构建了具有聚乙烯基团降解酶途径的工程解淀粉芽孢杆菌（BCAv-PEase），以增强对PE微塑料（PE-MPs）的降解。BCAv-PEase通过上调解聚酶、脱氢酶和过氧化氢酶的活性，增加了PE-MPs的生物降解，促进了PE薄膜的重量损失，提高了表面张力，并降低了PE的表面疏水性。机制分析表明，BCAv-PEase通过促进PEase的分泌来降解PE-MPs，从而导致PE-MPs底物中产生新的含氧官能团，这进一步加速了PE-MPs的代谢途径。对PE-MPs降解过程中微生物群落的分析表明，BCAv-PEase成为主要的细菌参与者，并刺激了与PE生物降解相关的微生物和功能基因的丰度。总之，本研究提供了一种由BCAv-PEase介导的PE-MPs生物降解的潜在机制，即通过调节底物选择性和优化生物催化途径来实现。
