真菌-生物炭协同增效降解四环素:性能、途径与转录组学解析

Synergistic degradation of tetracycline by Fungi-Biochar: Performance, pathways and transcriptomic analysis

摘要

水环境中残留的四环素类抗生素因其持久性、生物毒性及诱导耐药性而构成生态风险,微生物修复则是一种环境友好、高效且可靠的应对策略。本研究筛选到一株高效降解四环素的真菌,命名为季也蒙毕赤酵母 LUK1,并与铁改性生物炭(FeBC)复合,成功构建了生物炭菌剂(FeBC-LUK1)。结果表明,FeBC-LUK1在96 h内对四环素的降解率为95.36%,降解速率常数为游离真菌(77.20%)的1.71倍,在高四环素浓度(1 000 mg·L^-1)、高盐(NaCl,5%)及重金属(Cr^6＋/Co^2＋)胁迫下,降解效率较游离真菌LUK1分别提升45.39%、43.34%和56.32%、84.22%。SEM、FTIR、XPS及电化学测试等分析表明,FeBC凭借其多孔结构为菌株提供了定殖载体并促进生物膜形成。同时其负载的铁物种与增强的电子传递能力共同优化了降解微界面,从而协同提升了菌株LUK1的降解效率。液质联用鉴定出14种降解产物,推断其主要通过C4位点修饰、C6氧化裂解及去功能化等途径降解。转录组分析表明,真菌LUK1通过激活氧化还原酶系统、抗氧化酶系统及脂代谢通路以响应胁迫并催化降解。本研究为抗生素污染治理提供了理论支持与高效修复材料。

Abstract

Residual tetracycline antibiotics in aquatic environments present ecological risks owing to their persistence, biological toxicity, and potential to induce antimicrobial resistance. Microbial remediation represents an environmentally friendly, efficient, and reliable strategy to tackle this problem. This study isolated a highly efficient tetracycline-degrading fungus, Meyerozyma guilliermondii LUK1, and immobilized it on iron-modified biochar (FeBC) to fabricate a composite agent (FeBC-LUK1). The results show that FeBC-LUK1 agent achieves 95.36% tetracycline removal within 96 hours, with a degradation rate constant 1.71-fold higher than that of the free cells (77.20%). Notably, under stresses of high tetracycline concentration (1 000 mg·L^-1), high salinity (5% NaCl) and heavy metals (Cr^6＋ or Co^2＋), the degradation efficiency of FeBC-LUK1 is significantly enhanced by 45.39%, 43.34%, 56.32%, and 84.22%, respectively, compared to that of the free fungus. Analyses including SEM, FTIR, XPS, and electrochemical measurements demonstrate that FeBC, by virtue of its porous architecture, serves as a colonization scaffold for the bacterial strain and facilitates biofilm formation. Concurrently, the iron species immobilized on FeBC, in conjunction with its enhanced electron transfer capacity, collectively optimize the degradation microinterface, thereby synergistically enhancing the degradation efficiency of strain LUK1. 14 degradation products were identified by LC-MS, and three primary pathways were proposed: C4-site modification, C6-oxidation cleavage, and defunctionalization. Transcriptomic analysis further indicates that fungal strain LUK1 responds to tetracycline stress and facilitates its degradation by activating redox enzymes, antioxidant systems, and lipid metabolism pathways. This work provides both theoretical insights and efficient remediation material for the treatment of antibiotic contamination.

关键词

四环素降解 / 季也蒙毕赤酵母 / 铁改性生物炭 / 降解途径 / 转录组分析

Key words

tetracycline degradation / Meyerozyma guilliermondii / iron-modified biochar / degradation pathway / transcriptomic analysis

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基金资助

国家自然科学基金项目(22408237);新疆生产建设兵团指导性科技计划项目(2023ZD080);新疆生产建设兵团自然科学支持计划项目(2024DA052)