Control of bacterial biofilm communities by protozoans under semi-natural conditions

生物膜是与固体基质结合在一起的微生物群落，在水生生态系统的物质流动中起着重要作用。在本研究过程中，计划首次分析单细胞食草动物(原生动物)在半自然条件下控制生物膜细菌群落结构的作用。生物膜将建立在微室(流动细胞)中，接种来自莱茵河的天然水(放牧成分将在这里通过粒度分级进行控制)，或者通过复杂细菌群落的田间分离结合特定放牧动物的受控添加来接种。这些不同的方法将被用来测试具有不同复杂性的天然食草动物群落的影响(要么只包含鞭毛虫作为第一级消费者，要么包含额外的纤毛虫作为更高级别的消费者)，或者测试特定食草动物物种的影响。将考虑生物膜发展的不同阶段。细菌群落的形态结构将通过共聚焦激光扫描显微镜进行分析，其组成将通过DNA指纹图谱方法(DGGE)结合相关条带的测序进行分析。控制细菌生物被膜的预期结果与包括环境和应用微生物生态学在内的不同研究领域有关。

Biofilms, the complex communities of microbiota in association with solid substrates, play an important role in the matterflux of aquatic ecosystems. In the course of the present study it is planned to analyze for the first time the role of unicellular grazers (protozoans) in controlling the structure of biofilm-dwelling bacteria communities under semi-natural conditions. The biofilms will be established in micro-chambers ( flow cells ) and inoculated by either natural water from the River Rhine (the grazer composition will be manipulated by size fractionation here) or by field isolates of complex bacterial communities in combination with the controlled addition of specific grazers. These different approaches will be applied to test the effects of natural grazer communities with different complexities (containing either flagellates as first order-consumers alone, or additional ciliates as higher-order consumers), or the effects of specific grazer species. Different stages of the biofilm development will be considered. The morphological structure of the bacterial communities will be analyzed by confocal laser-scanning microscopy, its composition by a DNA-fingerprinting method (DGGE) in combination with sequencing of relevant bands. The expected results on the control of bacterial biofilms are relevant for different research areas including environmental and applied microbial ecology.