Institute of Microbiology, Guangdong Academy of Sciences, State Key Laboratory of Applied Microbiology Southern China, Guangzhou 510070, China.
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Int J Environ Res Public Health. 2022 Oct 11;19(20):12995. doi: 10.3390/ijerph192012995.
Freshwater biofilms play an important role in the migration and transformation of organic pollutants, especially under illumination conditions. Nonetheless, the roles of variable fractions in freshwater biofilms, e.g., extracellular polymeric substances (EPS), microbial cells and original biofilms, in promoting the photodegradation of trace organic pollutants remain largely unclear. In this study, two contaminants, i.e., methyl orange (MO) and bisphenol A (BPA), were selected, and the roles of different fractions in freshwater biofilms in their photodegradation performances were investigated. After dosing 696 mg/L SS biofilm harvested from an effluent-receiving river, the direct photodegradation rate of MO and BPA was increased 8.7 times and 5.6 times, respectively. River biofilm EPS contained more aromatic fractions, chromogenic groups and conjugated structures than biofilm harvested from a less eutrophic pond, which might be responsible for the enhanced photodegradation process. The quenching experiments suggested that when EPS fractions derived from river biofilm were dosed, EPS* was the major reactive oxygen species during the photodegradation of MO and BPA. Meanwhile, for EPS derived from the pond biofilm, ·OH/O was predominantly responsible for the enhanced photodegradation. Batch experimental results suggested that the cells and EPS in river biofilms could collaboratively interact with each other to enhance the preservation of reactive species and protection of microbes, thus facilitating the photoactivity of biofilms. Our results might suggest that biofilms generated from eutrophic waterbodies, such as effluent-receiving rivers, could play a more important role in the photodegradation processes of contaminants.
淡水生物膜在有机污染物的迁移和转化中起着重要作用，特别是在光照条件下。然而，在促进痕量有机污染物的光降解方面，淡水生物膜中不同组分（如胞外聚合物物质 (EPS)、微生物细胞和原始生物膜）的作用在很大程度上仍不清楚。本研究选择了两种污染物，即甲基橙 (MO) 和双酚 A (BPA)，并研究了淡水生物膜中不同组分在其光降解性能中的作用。在投加 696mg/L SS 从受纳河流中收获的生物膜后，MO 和 BPA 的直接光降解速率分别提高了 8.7 倍和 5.6 倍。与从贫营养池塘中收获的生物膜相比，河流生物膜 EPS 含有更多的芳香族部分、生色团和共轭结构，这可能是增强光降解过程的原因。猝灭实验表明，当投加源自河流生物膜的 EPS 时，EPS*是 MO 和 BPA 光降解过程中的主要活性氧物质。同时，对于源自池塘生物膜的 EPS，·OH/O是增强光降解的主要原因。批量实验结果表明，河流生物膜中的细胞和 EPS 可以相互协作，共同促进活性物质的保存和微生物的保护，从而提高生物膜的光活性。我们的结果可能表明，来自富营养水体（如受纳河流）的生物膜可能在污染物的光降解过程中发挥更重要的作用。
