近日，大湾区城市环境安全与绿色发展教育部重点实验室学术骨干陈姗姗教授课题组和福建农林大学资源与环境学院周顺桂教授团队在无氧-有氧区域的微塑料（microplastic, MP）降解研究方面取得重要进展，在环境领域著名期刊《Water Research》等上发表系列论文。从野外原位底泥实验、实验室泥柱实验及纯菌实验三个层面，证实铁还原菌驱动的类芬顿反应产生的羟基自由基（•OH）可以促进聚苯乙烯MP的降解，为微生物驱动类芬顿反应在自然界降解MP中的作用提供了直接证据，也为微生物降解微塑料研究提供了一种新的思路。

    论文DOI：

https://doi.org/10.1016/j.watres.2021.117782

https://doi.org/10.1016/j.watres.2022.118979

环境中MP分布广泛、尺寸微小（< 5 mm），污染作用持久，对生物生存造成的负面影响会威胁生态系统的健康与稳定，最终损害人类健康。MP的老化行为（也称降解、风化）是自然环境中普遍存在的现象，迄今为止被报道的MP老化行为大多发生在光照、开放和环境条件稳定的区域，而在黑暗和波动的无氧-有氧的区域却研究甚少。自然界中的交替无氧-有氧环境（如潮间带）是MP的集中分布区，随着淹水状态改变，其氧化还原电位不断变化，因此也是自由基产生的热区，该区域可能存在独特的微塑料降解途径。

基于此，本研究首先采用野外原位底泥实验和泥柱实验对聚苯乙烯微塑料（PS-MPs）在持续无氧、持续有氧、及交替无氧-有氧的底泥环境中的降解进行研究，随后以兼性厌氧的Shewanella putrefaciens 200为代表性异化铁还原微生物构建纯培养体系，揭示交替无氧-有氧环境中铁还原菌驱动的类芬顿反应产生•OH促进MP降解的机制。

英文摘要：

In the in-situ experiment, both the weight losses and O/C ratios of PS-MPs aged under alternating anoxic-oxic conditions were ∼2 times higher than those aged under static oxic and static anoxic conditions during 2-month experiments. In a 2-month column experiment, the PS-MPs in the alternating anoxic-oxic group showed weight losses and O/C ratios that were, respectively, triple and double the corresponding values for the static oxic and static anoxic groups. Column and pure-culture experiments demonstrated that dark production of ·OH which showed a positive correlation with a Fe redox process could explain enhanced MP aging under the alternating anoxic-oxic conditions. These findings provide a basis for risk assessment and management of MPs in the natural environment, such as in intertidal zones and paddy fields, and also have implications for engineering of optimized MP degradation processes.

Mechanisms of polystyrene microplastic degradation by the microbially driven Fenton reaction Natural hydroxyl radical (·OH) production, which partially occurs through the microbially driven Fenton reaction, can enhance the degradation of polystyrene microplastics (PS-MPs). However, ·OH causes damage to microorganisms, which might in turn restrain the microbially driven Fenton reaction. Thus, whether PS-MPs can be continuously degraded by the microbially driven Fenton reaction and how they are degraded are still unknown. A pure-culture system using Shewanella putrefaciens 200 was set up to explore the effect and mechanism of microbially driven Fenton reaction on PS-MP degradation. In a 14-day operation, ·OH produced by the microbially driven Fenton reaction could degrade PS-MPs with a weight loss of 6.1 ± 0.6% and an O/C ratio of 0.6 (v.s. 0.6 ± 0.1% and 0.1, respectively, in the ·OH quenched group). Benzene ring derivatives such as 2-isopropyl-5-methyl-1-heptanol and nonahexacontanoic acid were the main soluble products of PS-MP degradation. The ·OH-induced oxidative damage on microorganisms did not affect ·OH production significantly when there was timely replenishment of organic carbon sources to promote reproduction of microorganisms. Thus, PS-MPs can be continuously degraded by microbially driven Fenton reactions in natural alternating anaerobic-aerobic environments. This study also provides a new microbial technique for MP degradation that is different from previous technologies based on microbial plastic-degrading enzymes.