Perujo Nuria, Graeber Daniel, Fink Patrick, Neuert Lola, Sunjidmaa Nergui, Weitere Markus
Department of River Ecology, Helmholtz Centre for Environmental Research-UFZ, Magdeburg, Germany.
Department of Aquatic Ecosystem Analysis, Helmholtz Centre for Environmental Research - UFZ, Magdeburg, Germany.
Environ Microbiol Rep. 2025 Jun;17(3):e70115. doi: 10.1111/1758-2229.70115.
Phosphorus (P) dynamics at the sediment-water interface of aquatic ecosystems are receiving increasing attention due to their implications for water quality. P uptake by microbial biofilms can serve as a mechanism to control and mitigate the risk of eutrophication. Microbial biofilms capture P both intracellularly and extracellularly. While the significance of extracellular P entrapment in biofilms in engineered systems has recently been established, little is known about its dynamics in aquatic ecosystems. Current research on eutrophication control predominantly emphasises nitrogen, phosphorus or nitrogen-phosphorus ratio-based approaches, often overlooking the potential indirect influence of bioavailable dissolved organic carbon (DOC) on P uptake by heterotrophic microorganisms. In this study, we tested the effect of bioavailable DOC on P entrapment patterns in biofilms and in biofilm P-regulation mechanisms such as polyphosphate accumulation and alkaline phosphatase activity in semi-natural flow-through experimental flumes. Our results show that intracellular P entrapment is limited by bioavailable DOC, while extracellular P entrapment is independent of bioavailable DOC and has the potential to offset intracellular P saturation. We further demonstrate that DOC bioavailability influences benthic P cycling and that its implications extend into critical areas of ecosystem functioning such as river self-purification, competitive resource utilisation and organic P cycling.
由于磷对水质的影响，水生生态系统沉积物 - 水界面的磷（P）动态受到越来越多的关注。微生物生物膜对磷的吸收可作为控制和减轻富营养化风险的一种机制。微生物生物膜通过细胞内和细胞外两种方式捕获磷。虽然最近已经确定了工程系统中生物膜细胞外磷截留的重要性，但对其在水生生态系统中的动态了解甚少。目前关于富营养化控制的研究主要强调基于氮、磷或氮磷比的方法，常常忽视生物可利用溶解有机碳（DOC）对异养微生物吸收磷的潜在间接影响。在本研究中，我们在半天然流通实验水槽中测试了生物可利用DOC对生物膜中磷截留模式以及生物膜磷调节机制（如多聚磷酸盐积累和碱性磷酸酶活性）的影响。我们的结果表明，细胞内磷截留受生物可利用DOC的限制，而细胞外磷截留与生物可利用DOC无关，并且有可能抵消细胞内磷的饱和。我们进一步证明，DOC的生物可利用性影响底栖磷循环，其影响延伸到生态系统功能的关键领域，如河流自净、竞争性资源利用和有机磷循环。
