Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA.
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA.
J Bacteriol. 2024 Apr 18;206(4):e0009524. doi: 10.1128/jb.00095-24. Epub 2024 Apr 2.
Bacterial communities exhibit complex self-organization that contributes to their survival. To better understand the molecules that contribute to transforming a small number of cells into a heterogeneous surface biofilm community, we studied acellular aggregates, structures seen by light microscopy in colony biofilms using light microscopy and chemical imaging. These structures differ from cellular aggregates, cohesive clusters of cells important for biofilm formation, in that they are visually distinct from cells using light microscopy and are reliant on metabolites for assembly. To investigate how these structures benefit a biofilm community we characterized three recurrent types of acellular aggregates with distinct geometries that were each abundant in specific areas of these biofilms. Alkyl quinolones (AQs) were essential for the formation of all aggregate types with AQ signatures outside the aggregates below the limit of detection. These acellular aggregates spatially sequester AQs and differentiate the biofilm space. However, the three types of aggregates showed differing properties in their size, associated cell death, and lipid content. The largest aggregate type co-localized with spatially confined cell death that was not mediated by Pf4 bacteriophage. Biofilms lacking AQs were absent of localized cell death but exhibited increased, homogeneously distributed cell death. Thus, these AQ-rich aggregates regulate metabolite accessibility, differentiate regions of the biofilm, and promote survival in biofilms.IMPORTANCE is an opportunistic pathogen with the ability to cause infection in the immune-compromised. It is well established that biofilms exhibit resilience that includes decreased susceptibility to antimicrobial treatment. This work examines the self-assembled heterogeneity in biofilm communities studying acellular aggregates, regions of condensed matter requiring alkyl quinolones (AQs). AQs are important to both virulence and biofilm formation. Aggregate structures described here spatially regulate the accessibility of these AQs, differentiate regions of the biofilm community, and despite their association with autolysis, correlate with improved colony biofilm survival.
细菌群落表现出复杂的自我组织，这有助于它们的生存。为了更好地理解有助于将少数细胞转化为异质表面生物膜群落的分子，我们使用显微镜和化学成像研究了无细胞聚集体，即在菌落生物膜中通过显微镜观察到的结构。这些结构与细胞聚集体不同，细胞聚集体是细胞凝聚的团块，对于生物膜的形成很重要，因为它们在显微镜下与细胞明显不同，并且依赖于代谢物进行组装。为了研究这些结构如何使生物膜群落受益，我们描述了三种具有不同几何形状的反复出现的无细胞聚集体类型，这些类型在这些生物膜的特定区域都很丰富。烷基喹诺酮（AQs）对于所有聚集体类型的形成都是必不可少的，并且在聚集体外部的 AQ 特征低于检测限。这些无细胞聚集体在空间上隔离 AQs，并使生物膜空间分化。然而，这三种类型的聚集体在大小、相关细胞死亡和脂质含量方面表现出不同的特性。最大的聚集体类型与空间上受限的细胞死亡共定位，而这种细胞死亡不是由 Pf4 噬菌体介导的。缺乏 AQs 的生物膜没有局部细胞死亡，但表现出增加的、均匀分布的细胞死亡。因此，这些富含 AQ 的聚集体调节代谢物的可及性，分化生物膜的区域，并促进生物膜中的存活。重要的是，它是一种机会性病原体，能够在免疫功能低下的人群中引起感染。生物膜表现出弹性，包括对抗菌治疗的敏感性降低，这一点已经得到了充分的证实。这项工作研究了生物膜群落中的自组装异质性，研究了无细胞聚集体，即需要烷基喹诺酮（AQs）的凝聚物质区域。AQs 对毒力和生物膜形成都很重要。这里描述的聚集体结构在空间上调节这些 AQs 的可及性，分化生物膜群落的区域，并且尽管与自溶有关，但与提高的生物膜存活率相关。
