Xia Chen, Yu Manyou, Deng Junlin, Tang Hao, Wang Yan, Li Yuan-Qiu
Institute of Agro-Products Processing Science and Technology, Institute of Food Nutrition and Health, Sichuan Academy of Agricultural Sciences, 610066 Chengdu, China.
College of Life Science, Leshan Normal University, Leshan 614000, China.
Bioresour Technol. 2025 Nov;436:133039. doi: 10.1016/j.biortech.2025.133039. Epub 2025 Jul 26.
The global plastic crisis demands innovative solutions for recycling polyethylene terephthalate (PET), a chemically stable polymer constituting 23 % of annual plastic waste. This study presents a significant advance in PET upcycling using engineered Halomonas sp. Y3, a halophilic bacterium uniquely suited for industrial bioprocessing. We addressed key challenges in PET valorization-inefficient assimilation of its depolymerized monomers, terephthalic acid (TPA) and ethylene glycol (EG)-through systematic metabolic engineering. First, TPA catabolism was enabled by integrating heterologous tph operons and transporters, achieving a 46 % higher TPA degradation rate (1.39 mmol/L·h) than Comamonas sp. E6 of 0.95 mmol/L·h. Concurrently, EG utilization was enhanced 6.3-fold (8.34 mmol/L·h) via glcDEFG overexpression and glyoxylate pathway optimization than wild-type Halomonas sp. Y3 (1.32 mmol/L·h). To overcome metabolic interference in single-strain systems, we pioneered a synthetic microbial consortium (PET_co) comprising two specialized Halomonas strains: one metabolizing EG and the other TPA. This consortium achieved complete co-utilization of mixed PET hydrolysates within 36 h, yielding 7.99 g/L polyhydroxyalkanoates (PHA)-2.4 × higher than monoculture controls (PET03, PET07, PET09)-without supplemental carbon. Notably, the strain halotolerance and alkaliphily enabled direct integration with alkaline PET depolymerization, bypassing costly sterilization. By synergizing chemical and biological processes, this work establishes Halomonas sp. Y3 as a robust platform for industrial-scale plastic upcycling, advancing circular economy strategies to mitigate plastic pollution.
全球塑料危机需要创新的解决方案来回收聚对苯二甲酸乙二酯（PET），这种化学性质稳定的聚合物占每年塑料垃圾的23%。本研究展示了利用工程化嗜盐单胞菌Y3在PET升级循环利用方面取得的重大进展，该嗜盐细菌特别适合工业生物处理。我们通过系统的代谢工程解决了PET增值过程中的关键挑战，即其解聚单体对苯二甲酸（TPA）和乙二醇（EG）的同化效率低下问题。首先，通过整合异源tph操纵子和转运蛋白实现了TPA分解代谢，TPA降解率达到1.39 mmol/L·h，比食酸丛毛单胞菌E6的0.95 mmol/L·h高出46%。同时，通过过表达glcDEFG和优化乙醛酸途径，EG利用率比野生型嗜盐单胞菌Y3（1.32 mmol/L·h）提高了6.3倍（8.34 mmol/L·h）。为了克服单菌株系统中的代谢干扰，我们开创了一种合成微生物群落（PET_co），它由两种特殊的嗜盐单胞菌菌株组成：一种代谢EG，另一种代谢TPA。该群落能够在36小时内完全共同利用混合的PET水解产物，产生7.99 g/L的聚羟基脂肪酸酯（PHA），比单培养对照（PET03、PET07、PET09）高出2.4倍，且无需补充碳源。值得注意的是，该菌株的耐盐性和嗜碱性使其能够直接与碱性PET解聚过程整合，绕过了成本高昂的灭菌步骤。通过将化学和生物过程协同作用，这项工作将嗜盐单胞菌Y3确立为工业规模塑料升级循环利用的强大平台，推动了循环经济战略以减轻塑料污染。
