Thomen Philippe, Robert Jérôme, Monmeyran Amaury, Bitbol Anne-Florence, Douarche Carine, Henry Nelly
Sorbonne Universités, UPMC Univ Paris 06 & CNRS, UMR 8237, Laboratoire Jean Perrin, Paris, France.
Université Paris Sud, UMR 8502, Laboratoire de Physique des Solides, Orsay, France.
PLoS One. 2017 Apr 12;12(4):e0175197. doi: 10.1371/journal.pone.0175197. eCollection 2017.
Bacterial communities attached to surfaces under fluid flow represent a widespread lifestyle of the microbial world. Through shear stress generation and molecular transport regulation, hydrodynamics conveys effects that are very different by nature but strongly coupled. To decipher the influence of these levers on bacterial biofilms immersed in moving fluids, we quantitatively and simultaneously investigated physicochemical and biological properties of the biofilm. We designed a millifluidic setup allowing to control hydrodynamic conditions and to monitor biofilm development in real time using microscope imaging. We also conducted a transcriptomic analysis to detect a potential physiological response to hydrodynamics. We discovered that a threshold value of shear stress determined biofilm settlement, with sub-piconewton forces sufficient to prevent biofilm initiation. As a consequence, distinct hydrodynamic conditions, which set spatial distribution of shear stress, promoted distinct colonization patterns with consequences on the growth mode. However, no direct impact of mechanical forces on biofilm growth rate was observed. Consistently, no mechanosensing gene emerged from our differential transcriptomic analysis comparing distinct hydrodynamic conditions. Instead, we found that hydrodynamic molecular transport crucially impacts biofilm growth by controlling oxygen availability. Our results shed light on biofilm response to hydrodynamics and open new avenues to achieve informed design of fluidic setups for investigating, engineering or fighting adherent communities.
附着在流体流动下表面的细菌群落代表了微生物世界中一种广泛存在的生存方式。通过产生剪切应力和调节分子运输，流体动力学传递的效应本质上截然不同但又紧密耦合。为了解析这些因素对浸没在流动流体中的细菌生物膜的影响，我们对生物膜的物理化学和生物学特性进行了定量且同步的研究。我们设计了一种微流控装置，能够控制流体动力学条件，并使用显微镜成像实时监测生物膜的形成。我们还进行了转录组分析，以检测对流体动力学的潜在生理反应。我们发现，剪切应力的阈值决定了生物膜的沉降，亚皮牛顿力足以阻止生物膜的形成。因此，设定剪切应力空间分布的不同流体动力学条件促进了不同的定殖模式，对生长模式产生影响。然而，未观察到机械力对生物膜生长速率有直接影响。同样，在我们比较不同流体动力学条件的差异转录组分析中，未出现机械传感基因。相反，我们发现流体动力学分子运输通过控制氧气供应对生物膜生长至关重要。我们的研究结果揭示了生物膜对流体动力学的反应，并为实现用于研究、工程设计或对抗附着群落的流体装置的明智设计开辟了新途径。
