Limnological Station, Department of Plant and Microbial Biology, University of Zurich, Switzerland.
Limnological Station, Department of Plant and Microbial Biology, University of Zurich, Switzerland.
Syst Appl Microbiol. 2018 May;41(3):221-231. doi: 10.1016/j.syapm.2017.11.009. Epub 2017 Dec 21.
Gravity-driven membrane (GDM) filtration is a promising tool for low-cost decentralized drinking water production. The biofilms in GDM systems are able of removing harmful chemical components, particularly toxic cyanobacterial metabolites such as microcystins (MCs). This is relevant for the application of GDM filtration because anthropogenic nutrient input and climate change have led to an increase of toxic cyanobacterial blooms. However, removal of MCs in newly developing GDM biofilms is only established after a prolonged period of time. Since cyanobacterial blooms are transient phenomena, it is important to understand MC removal in mature biofilms with or without prior toxin exposure. In this study, the microbial community composition of GDM biofilms was investigated in systems fed with water from a lake with periodic blooms of MC-producing cyanobacteria. Two out of three experimental treatments were supplemented with dead biomass of a MC-containing cyanobacterial strain, or of a non-toxic mutant, respectively. Analysis of bacterial rRNA genes revealed that both biomass-amended treatments were significantly more similar to each other than to a non-supplemented control. Therefore, it was hypothesized that biofilms could potentially be 'primed' for rapid MC removal by prior addition of non-toxic biomass. A subsequent experiment showed that MC removal developed significantly faster in mature biofilms that were pre-fed with biomass from the mutant strain than in unamended controls, indicating that MC degradation was a facultative trait of bacterial populations in GDM biofilms. The significant enrichment of bacteria related to both aerobic and anaerobic MC degraders suggested that this process might have occurred in parallel in different microniches.
重力驱动膜 (GDM) 过滤是一种有前途的低成本分散式饮用水生产工具。GDM 系统中的生物膜能够去除有害的化学成分，特别是有毒的蓝藻代谢物，如微囊藻毒素 (MCs)。这对于 GDM 过滤的应用非常重要，因为人为的营养输入和气候变化导致有毒蓝藻水华的增加。然而，在新形成的 GDM 生物膜中去除 MCs 仅在经过长时间后才能建立。由于蓝藻水华是短暂的现象，因此了解成熟生物膜中是否存在先前暴露于毒素的情况下 MC 的去除情况非常重要。在这项研究中，研究了从周期性产生 MC 的蓝藻水华的湖泊中供水的 GDM 生物膜的微生物群落组成。三个实验处理中有两个分别补充了含有 MC 的蓝藻菌株或无毒突变体的死生物量。细菌 rRNA 基因分析表明，两个生物量添加处理彼此之间的相似性明显高于未添加对照。因此，假设通过先前添加无毒生物量，可以使生物膜“预先准备”以快速去除 MC。随后的实验表明，在成熟的生物膜中预先喂食突变体菌株的生物量后，MC 的去除速度明显加快，而未添加对照则明显加快，这表明 MC 降解是 GDM 生物膜中细菌种群的兼性特征。与好氧和厌氧 MC 降解菌都有关的细菌的显著富集表明，该过程可能在不同的微生境中同时发生。
