Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Göteborg, Sweden.
Department of Industrial and Materials Science, Chalmers University of Technology, 412 96 Göteborg, Sweden.
Int J Mol Sci. 2020 Sep 15;21(18):6755. doi: 10.3390/ijms21186755.
Bacteria are known to form biofilms on various surfaces. Biofilms are multicellular aggregates, held together by an extracellular matrix, which is composed of biological polymers. Three principal components of the biofilm matrix are exopolysaccharides (EPS), proteins, and nucleic acids. The biofilm matrix is essential for biofilms to remain organized under mechanical stress. Thanks to their polymeric nature, biofilms exhibit both elastic and viscous mechanical characteristics; therefore, an accurate mechanical description needs to take into account their viscoelastic nature. Their viscoelastic properties, including during their growth dynamics, are crucial for biofilm survival in many environments, particularly during infection processes. How changes in the composition of the biofilm matrix affect viscoelasticity has not been thoroughly investigated. In this study, we used interfacial rheology to study the contribution of the EPS component of the matrix to viscoelasticity of biofilms. Two strategies were used to specifically deplete the EPS component of the biofilm matrix, namely (i) treatment with sub-lethal doses of vitamin C and (ii) seamless inactivation of the operon responsible for biosynthesis of the EPS. In both cases, the obtained results suggest that the EPS component of the matrix is essential for maintaining the viscoelastic properties of bacterial biofilms during their growth. If the EPS component of the matrix is depleted, the mechanical stability of biofilms is compromised and the biofilms become more susceptible to eradication by mechanical stress.
细菌已知会在各种表面形成生物膜。生物膜是由细胞外基质（extracellular matrix）聚集在一起的多细胞体，由生物聚合物组成。生物膜基质的三个主要成分是胞外多糖（EPS）、蛋白质和核酸。生物膜基质对于生物膜在机械应力下保持组织有序性至关重要。由于其聚合性质，生物膜表现出弹性和粘性的机械特性；因此，准确的机械描述需要考虑其粘弹性性质。它们的粘弹性特性，包括在生长动力学期间的特性，对于生物膜在许多环境中的生存至关重要，特别是在感染过程中。生物膜基质组成的变化如何影响粘弹性尚未得到彻底研究。在这项研究中，我们使用界面流变学来研究基质 EPS 成分对生物膜粘弹性的贡献。我们使用了两种策略来专门消耗生物膜基质的 EPS 成分，即（i）用亚致死剂量的维生素 C 处理，以及（ii）无缝失活负责 EPS 生物合成的 operon。在这两种情况下，所得结果表明，基质的 EPS 成分对于在生物膜生长过程中维持其粘弹性特性是必不可少的。如果消耗了基质的 EPS 成分，生物膜的机械稳定性就会受到损害，生物膜更容易受到机械应力的清除。
