Crack patterns of drying dense bacterial suspensions. Issue 28 (30th June 2022)

• Record Type: Journal Article
• Authors: Ma, Xiaolei; Liu, Zhengyang; Zeng, Wei; Lin, Tianyi; Tian, Xin; Cheng, Xiang
• Is Part Of: Soft matter. Volume 18:Issue 28(2022)
• Page Start: 5239
• Page End: 5248
• Publication Date: 2022-06-30
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/d2sm00012a
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : We explored mechanical instabilities developed during the drying of dense suspensions of bacteria with distinct motile behaviors, which is an ubiquitous process in natural and engineering settings. Abstract : Drying of bacterial suspensions is frequently encountered in a plethora of natural and engineering processes. However, the evaporation-driven mechanical instabilities of dense consolidating bacterial suspensions have not been explored heretofore. Here, we report the formation of two different crack patterns of drying suspensions of Escherichia coli ( E. coli ) with distinct motile behaviors. Circular cracks are observed for wild-type E. coli with active swimming, whereas spiral-like cracks form for immotile bacteria. Using the elastic fracture mechanics and the poroelastic theory, we show that the formation of the circular cracks is determined by the tensile nature of the radial drying stress once the cracks are initiated by the local order structure of bacteria due to their collective swimming. Our study demonstrates the link between the microscopic swimming behaviors of individual bacteria and the mechanical instabilities and macroscopic pattern formation of drying bacterial films. The results shed light on the dynamics of active matter in a drying process and provide useful information for understanding various biological processes associated with drying bacterial suspensions.