Helmholtz Centre for Environmental Research - UFZ, Department River Ecology, Brückstraße 3a, 39114 Magdeburg, Germany.
Protist. 2012 Jul;163(4):632-42. doi: 10.1016/j.protis.2011.10.008. Epub 2011 Dec 18.
Here we present a new approach to quantify food-web interactions within semi-natural biofilms by combining the establishment of biofilms from natural rivers in flow cells with video microscopy. In a first application of this approach, we focused on the surface-gliding heterotrophic flagellates (HF) Neobodo designis, Rhynchomonas nasuta and Planomonas sp. It was shown that the three HF generally ingested single biofilm-associated bacteria whereas bacteria within microcolonies were attacked but not ingested. However, grazing strategies differed considerably. While the kinetoplastids N. designis and R. nasuta displayed long search and short handling times, Planomonas sp. showed the opposite grazing characteristics. The latter behaviour resulted in a high relative predation success of 80% (precent of attacked prey ingested), whereas the relative predation success of the two kinetoplastids was only 20%. However, the two contrasting strategies resulted in similar ingestion rates for Planomonas sp. and N. designis of 0.5 to 0.6 ingestions flagellates(-1) minute(-1), respectively. Our results showed distinct differences in the feeding behaviour of three flagellates having similar life forms and provide direct evidence that microcolony formation in biofilms protects bacteria from grazing by HF in situ. The new approach provides individual-based insights into the complex food web interactions within biofilms.
我们提出了一种新的方法，通过在流动池中从天然河流中建立生物膜并结合视频显微镜来定量半自然生物膜中的食物网相互作用。在这种方法的首次应用中，我们专注于表面滑行异养鞭毛虫（HF）Neobodo designis、Rhynchomonas nasuta 和 Planomonas sp。结果表明，这三种 HF 通常摄取单个生物膜相关细菌，而微菌落中的细菌则受到攻击但未被摄取。然而，摄食策略差异很大。虽然动基体鞭毛虫 N. designis 和 R. nasuta 表现出长搜索和短处理时间，而 Planomonas sp. 则表现出相反的摄食特征。后者的行为导致相对捕食成功率高达 80%（被攻击猎物的百分比被摄取），而两种动基体鞭毛虫的相对捕食成功率仅为 20%。然而，这两种截然不同的策略导致 Planomonas sp. 和 N. designis 的摄取率相似，分别为 0.5 到 0.6 个鞭毛虫(-1)分钟(-1)。我们的研究结果表明，具有相似生活方式的三种鞭毛虫在摄食行为上存在明显差异，并提供了直接证据表明，生物膜中的微菌落形成原位保护细菌免受 HF 的摄食。这种新方法提供了个体层面上对生物膜中复杂食物网相互作用的深入了解。
