Enhanced effects of biochar-immobilised dual-functional E. quasihormaechei on PPST degradation and nitrogen conservation in nitrogen-deficient composting

作者：Yanjiao Qi, Long Cao, Shen Yang, Qian Li, Jiazhi Gao, Linshan Wang, Yamin Zhao, Junyan Liu, Hong Zhang · 发表于：Environmental Technology & Innovation · 年份：2025 · DOI：10.1016/j.eti.2025.104544 · 被引用次数：4 · 研究领域：Composting and Vermicomposting Techniques

The inherently high C/N ratio of polyester plastics, such as PPST, creates a severe nitrogen (N) deficiency during composting, while thermophilic conditions exacerbate N loss. These dual constraints critically limit the biodegradation efficiency and compost quality. In this study, a novel dual-functional strain Enterobacter quasihormaechei (EQ1) demonstrated the capability of utilizing PBAT (a key component of PPST) as its sole carbon source while concurrently performing biological nitrogen fixation, which was first identified and isolated from plastic compost. To enhance its efficacy and stability, EQ1 was also immobilized on biochar (forming CEQ) and introduced into nitrogen-deficient PPST composting systems. The CEQ amendment significantly boosted PPST degradation rates to 85.7 %-93.8 %, overcoming the nitrogen limitation barrier. Simultaneously, CEQ dramatically mitigated nitrogen loss by 16.3 % and accelerated the transformation of compost N into available forms (NH 4 + -N/NO 3 - -N), significantly enhancing compost maturity (GI=99 %). Metagenomic analysis revealed PPST hydrolysis by lipase/carboxylesterase, producing characteristic oligomers, such as 6-(4-hydroxybutoxy)-6-oxohexanoic acid and 2-((2-hydroxypropanoyl)oxy) propanoic acid, etc. The co-activation of nitrogen cycling was evidenced by the improved indicators, such as nitrogen-fixing enzyme (218 IU/L), nitrite oxidoreductase (85.2 IU/L), and the related genes nifH (6.3 ×10⁴ copies/mg) and nxrA (7.6 ×10⁴ copies/...