Abstract Two key factors were identified that enhance remediation of a hypereutrophic reservoir colonised by Eichhornia heterosperma Alexander, 1939. These factors are the high abundance of the microbial community in root-associated biofilms and their high extracellular enzyme activity (EEA). The capacity of macrophytes for nutrients removal has been widely acknowledged. However, there has been little discussion on the role of root-associated biofilms in enhancing phytoremediation. We determined nutrient levels across the reservoir quarterly during two years. We assessed the structure of the microbial community in water, root-associated biofilms, and sediments along with their phosphatase and β-glucosidase activities. We hypothesised that reservoir remediation is enhanced by increased nutrient remineralisation and bioavailability, arising from EEA in root-associated biofilms attached to E. heterosperma. Sedimentation removed 51% of the total nitrogen (TN) and 85% of the total phosphorus (TP) external load. E. heterosperma and its root-associated biofilms removed extra 8% TN and 7% TP. The abundance of the microbial community in root-associated biofilms was generally higher than in water and sediment, being dominated by Alphaproteobacteria and Betaproteobacteria. The EEA in root-associated biofilms ranged 117−1760 μmol g−1 wet weight h−1 for phosphatase and 107−676 μmol g−1 wet weight h−1 for β-glucosidase, indicating high mineralisation rates. These results showed that the microbial community in root-associated biofilms favours reservoir remediation by supplying mineralised nutrients to algae and macrophytes, but the permanent introduction of high nutrient loads exceeds the reservoir capacity for remediation. Improving the trophic state of the reservoir requires thus long-term strategies at basin scale for reducing the nutrient loads.

中文翻译：

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Eichhornia heterosperma Alexander 的根相关生物膜，1939 年有助于修复哥伦比亚 Porce II 热带水库

摘要 1939 年，确定了两个关键因素，可以增强对异种 Eichhornia Alexander 定植的超富营养化水库的修复。这些因素是根相关生物膜中微生物群落的高丰度及其高细胞外酶活性 (EEA)。大型植物去除养分的能力已得到广泛认可。然而，关于根相关生物膜在增强植物修复中的作用的讨论很少。我们在两年内每季度确定整个水库的营养水平。我们评估了水中微生物群落、根相关生物膜和沉积物的结构以及它们的磷酸酶和 β-葡萄糖苷酶活性。我们假设通过增加养分再矿化和生物利用度来增强水库修复，由 EEA 中的根相关生物膜引起，附着在 E.heterosperma 上。沉淀去除了 51% 的总氮 (TN) 和 85% 的总磷 (TP) 外部负荷。E.heterosperma 及其根相关生物膜去除了额外的 8% TN 和 7% TP。根相关生物膜中微生物群落的丰度通常高于水和沉积物，主要是 Alphaproteobacteria 和 Betaproteobacteria。根相关生物膜中的 EEA 范围为 117-1760 μmol g-1 磷酸酶湿重 h-1 和 107-676 μmol g-1 湿重 h-1 β-葡萄糖苷酶，表明高矿化率。这些结果表明，根相关生物膜中的微生物群落有利于通过向藻类和大型植物提供矿化养分来修复水库，但长期引入高营养负荷超过了修复的水库容量。因此，改善水库的营养状态需要流域规模的长期战略，以减少养分负荷。