Heterogeneous gene expression, metabolic variability and differentiation in Staphylococcus epidermidis biofilms

表皮葡萄球菌是一种原型生物膜形成细菌，其特征在于生物膜群落内具有明显的表型变异性。本研究旨在了解S.表皮生物膜在上一个融资期，我们确定，在S。在表皮生物膜群体中，表型变体共存。它们在生物膜基质产生和代谢特性方面不同，其中不同的细菌亚群经历DNA的裂解和释放。此外，生物膜阴性变体在生物膜内以高频率出现。共聚焦激光扫描显微镜（CLSM）分析揭示了一个有组织的空间结构的S。表皮生物膜具有显著程度的异质基因表达模式和在生物膜的明确限定区域中的各种亚群的浓度。最引人注目的是，一个小的非编码RNA（即，RsaE）被鉴定为产生S.表皮生物膜群落。因此，RsaE应该介导蛋白质和多糖生物膜基质生产之间的（可逆）转换，最有可能通过葡萄球菌代谢的重新编程。同时，该分子也可能能够限制导致生物膜异质性的遗传事件的频率。由于RsaE本身是异质性表达的，我们建议这种核糖核酸调节因子作为产生和控制生物膜多样性的重要驱动因素发挥作用。为了证实这一假设，我们将在即将到来的资助期内特别关注介导S.表皮生物膜因此，我们将研究RsaE在这个过程中的分子功能，并研究其与其他重要的调节回路（如群体感应以及程序性细菌裂解和细胞死亡）的假定联系。此外，我们将继续通过共聚焦激光扫描显微镜分析生物膜发展的时空动力学，并将这些研究扩展到流动室模型。最后，我们将与联盟内的合作者共同努力，建立合适的模型来模拟和预测S。表皮生物膜的发育和多样化。

Staphylococcus epidermidis is a prototype biofilm-forming bacterium characterised by a pronounced phenotypic variability within biofilm communities. The proposed research aims at an understanding of the biological significance and the factors that trigger and control heterogeneity in S. epidermidis biofilms. In the previous funding period, we established that, within S. epidermidis biofilm populations, phenotypic variants coexist. They vary in terms of biofilm matrix production and metabolic properties, with distinct subpopulations of bacteria undergoing lysis and release of DNA. In addition, biofilm-negative variants arise in high frequencies within the biofilm. Confocal laser scanning microscopy (CLSM) analyses revealed an organised spatial structure of the S. epidermidis biofilms with a significant degree of heterogeneus gene expression patterns and the concentration of various subpopulations in well-defined regions of the biofilm. Most strikingly, a small non-coding RNA (i.e., RsaE) was identified to act as a putative trigger for generating heterogeneity in S. epidermidis biofilm communities. Thus, RsaE is supposed to mediate the (reversible) switch between protein- and polysaccharide-biofilm matrix production, most likely through re-programing of the staphylococcal metabolism. At the same time, the molecule is possibly capable of limiting the frequency of genetic events contributing to biofilm heterogeneity as well. As RsaE itself is heterogeneously expressed, we suggest this riboregulator to function as an important driver for generating and controlling biofilm diversity. To substantiate this, hypothesis we will, in the upcoming funding period, specifically focus on the factors and molecular mechanisms that mediate diversity in S. epidermidis biofilms. Thus, we will investigate the molecular function of RsaE in the process, and study its putative link to other important regulatory circuits such as quorum sensing as well as programmed bacterial lysis and cell death. Moreover, we will continue to analyse the spatiotemporal dynamics of biofilm development by confocal laser scanning microscopy and extend these studies to flow chamber models. Finally, in an joint effort with our collaborators within the consortium, we will establish suitable models to simulate and predict S. epidermidis biofilm development and diversification.