Recent experiments show that synthetic polymers can influence the degree of microbial aggregation and the rheological properties of bacterial suspensions, the study of which can help us control biofilm formation. In this article, we add polyethylene glycol (PEG) with various molecular weights and concentrations into two types Bacillus subtilis cell cultures, Luria Broth (LB) and Minimal Salts glutamate glycerol (MSgg), respectively. We first observe cell clusters in cell suspensions with various concentrations of PEG, and measure cluster size in both static and dynamic fluid environments. We find that cells gather together into big clusters and most of the cells are arranged longitudinally; and the large cell clusters are divided into smaller aggregates under fluid shear. We then use a rheometer to measure the viscoelastic properties of various cell cultures, to represent the degree of aggregation of the bacterial suspensions. We find the storage modulus, the loss modulus and the viscosity of bacterial suspensions not only depend on the cell aggregation but also depend on the directionality of cellular motion.

中文翻译：

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通过添加聚乙二醇诱导的生物膜介导的枯草芽孢杆菌悬浮液的粘弹性变化。

最近的实验表明，合成聚合物可以影响微生物聚集的程度和细菌悬浮液的流变特性，其研究可以帮助我们控制生物膜的形成。在本文中，我们将具有不同分子量和浓度的聚乙二醇（PEG）分别添加到两种类型的枯草芽孢杆菌细胞培养物中，分别是Luria Broth（LB）和Minimal Salts谷氨酸甘油（MSgg）。我们首先观察具有不同浓度PEG的细胞悬液中的细胞簇，并测量静态和动态流体环境中的簇大小。我们发现细胞聚集在一起成大簇，并且大多数细胞是纵向排列的。在流体剪切作用下，大的细胞团被分成较小的聚集体。然后，我们使用流变仪测量各种细胞培养物的粘弹性，以表示细菌悬浮液的聚集程度。我们发现细菌悬浮液的储能模量，损失模量和粘度不仅取决于细胞聚集，还取决于细胞运动的方向性。