Human infection by Legionella pneumophila (Lpn) only occurs via contaminated water from man-made sources, and eradication of these bacteria from man-made water systems is complicated by biofilm colonization. Using a continuously fed biofilm reactor model, we grew a biofilm consortium from potable water that was able to prolong recovery of Lpn CFU from biofilms. This effect was recreated using a subset of those species in a simplified consortium composed of eight bacterial isolates from the first biofilm reactor. In the reactor with the eight-species consortium, Lpn biofilm CFU was relatively stable over a 12-day trial. An isolate of Acidovorax from the consortium was, as a single species biofilm, able to promote Lpn surface attachment. Other isolates from the Pelomonas genus grew as equally robust biofilms alone, but did not promote surface attachment of Lpn. This attachment was disrupted by cationic polysaccharides and loss of the Lpn Lcl collagen-like adhesin protein. This work demonstrates that, while Lpn was fairly incompetent at attachment to surfaces to form a biofilm alone, pre-existing biofilms allowed attachment of Lpn as secondary colonizers. In addition, we demonstrate that initial attachment of Lpn to Acidovorax biofilms is likely via the Lcl-adhesin protein.

肺炎军团菌（Lpn）的人类感染仅通过来自人为来源的污染水发生，而从人为水系统中消灭这些细菌会因生物膜定殖而变得复杂。使用连续进料的生物膜反应器模型，我们从饮用水中培育了生物膜财团，从而能够延长从生物膜中回收Lpn CFU的速度。使用由来自第一个生物膜反应器的八个细菌分离物组成的简化财团中的这些物种的子集，可以重新产生这种效果。在具有8种物种的财团的反应堆中，经过12天的试验，Lpn生物膜CFU相对稳定。作为一个单一物种的生物膜，从财团中分离出的Acidovorax能够促进Lpn表面附着。Pelomonas属的其他分离株仅以同样坚固的生物膜生长，但不促进Lpn的表面附着。这种附着被阳离子多糖和Lpn Lcl胶原样粘附素蛋白的丢失所破坏。这项工作表明，虽然Lpn在附着于表面时不能完全形成单独的生物膜，但预先存在的生物膜却允许Lpn作为次生定居者附着。此外，我们证明了Lpn到Acidovorax生物膜的最初附着很可能是通过Lcl-粘附素蛋白实现的。