Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
J Bacteriol. 2019 Aug 22;201(18). doi: 10.1128/JB.00670-18. Print 2019 Sep 15.
Many microbes coexist within biofilms, or multispecies communities of cells encased in an extracellular matrix. However, little is known about the microbe-microbe interactions relevant for creating these structures. In this study, we explored a striking dual-species biofilm between and that exhibited characteristics that were not predictable from previous work examining monoculture biofilms. Coculture wrinkle formation required a exopolysaccharide as well as the amyloid-like protein TasA. Unexpectedly, other matrix components essential for monoculture biofilm formation were not necessary for coculture wrinkling (e.g., the exopolysaccharide EPS, the hydrophobin BslA, and cell chaining). In addition, cell chaining prevented coculture wrinkling, even though chaining was previously associated with more robust monoculture biofilms. We also observed that increasing the relative proportion of (which forms completely featureless monoculture colonies) increased coculture wrinkling. Using microscopy and rheology, we observed that these two bacteria assemble into an organized layered structure that reflects the physical properties of both monocultures. This partitioning into distinct regions negatively affected the survival of while also serving as a protective mechanism in the presence of antibiotic stress. Taken together, these data indicate that studying cocultures is a productive avenue to identify novel mechanisms that drive the formation of structured microbial communities. In the environment, many microbes form biofilms. However, the interspecies interactions underlying bacterial coexistence within these biofilms remain understudied. Here, we mimic environmentally relevant biofilms by studying a dual-species biofilm formed between and and subjecting the coculture to chemical and physical stressors that it may experience in the natural world. We determined that both bacteria contribute structural elements to the coculture, which is reflected in its overall viscoelastic behavior. Existence within the coculture can be either beneficial or detrimental depending on the context. Many of the features and determinants of the coculture biofilm appear distinct from those identified in monoculture biofilm studies, highlighting the importance of characterizing multispecies consortia to understand naturally occurring bacterial interactions.
许多微生物共存于生物膜中，或者是细胞的多物种群落被包裹在细胞外基质中。然而，对于形成这些结构相关的微生物-微生物相互作用，我们知之甚少。在这项研究中，我们探索了一种引人注目的 和 之间的双物种生物膜，它表现出的特征是以前研究单培养生物膜时无法预测的。共培养褶皱的形成需要 的胞外多糖以及 的类淀粉样蛋白 TasA。出乎意料的是，对于共培养褶皱形成来说，其他对于单培养生物膜形成至关重要的 基质成分并不是必需的（例如，胞外多糖 EPS、疏水性蛋白 BslA 和细胞链）。此外， 细胞链的存在阻止了共培养褶皱的形成，尽管之前已经观察到细胞链与更健壮的单培养生物膜相关。我们还观察到，增加 的相对比例（它形成完全没有特征的单培养菌落）增加了共培养褶皱的形成。通过显微镜和流变学观察，我们发现这两种细菌组装成一种有组织的分层结构，反映了两种单培养物的物理性质。这种分区进入不同的区域对 的生存产生负面影响，同时在存在抗生素压力的情况下也作为一种保护机制。总之，这些数据表明，研究共培养是一种很有成效的途径，可以确定驱动结构化微生物群落形成的新机制。在环境中，许多微生物形成生物膜。然而，在这些生物膜中细菌共存的种间相互作用仍然研究不足。在这里，我们通过研究 和 之间形成的双物种生物膜并对共培养物施加它在自然界中可能经历的化学和物理胁迫来模拟环境相关的生物膜。我们确定两种细菌都为共培养物提供了结构元素，这反映在其整体粘弹性行为中。在共培养物中的存在可能是有益的，也可能是有害的，这取决于具体情况。共培养生物膜的许多特征和决定因素似乎与单培养生物膜研究中确定的特征不同，这突出了表征多物种联合体以了解自然发生的细菌相互作用的重要性。
