A biophysical threshold for biofilm formation

Abstract

Bacteria are ubiquitous in our daily lives, either as motile planktonic cells or as immobilized surface-attached biofilms. These different phenotypic states play key roles in agriculture, environment, industry, and medicine; hence, it is critically important to be able to predict the conditions under which bacteria transition from one state to the other. Unfortunately, these transitions depend on a dizzyingly complex array of factors that are determined by the intrinsic properties of the individual cells as well as those of their surrounding environments, and are thus challenging to describe. To address this issue, here, we develop a generally-applicable biophysical model of the interplay between motility-mediated dispersal and biofilm formation under positive quorum sensing control. Using this model, we establish a universal rule predicting how the onset and extent of biofilm formation depend collectively on cell concentration and motility, nutrient diffusion and consumption, chemotactic sensing, and autoinducer production. Our work thus provides a key step toward quantitatively predicting and controlling biofilm formation in diverse and complex settings.

Stress anisotropy in confined populations of growing rods

“…It would be interesting to elucidate what role the effects discovered here can play among the complex processes that characterize natural systems. This includes nutrient distribution [16,35,36], which leads to gradients of activity and thereby represents another opportunity for the passive properties of the system to become important, but also extends to structure formation in three dimensions [20,35,36], interactions with other types of activity such as motility and chemical signal production [37] and different kinds of confinement [38]. In addition, it may prove rewarding to look for even more general physical principles by exploring the similarities the system exhibits to dense systems of active polymers and filaments [39,40] due to its columnar structure.…”

A computational model for microbial colonization of an antifouling surface

“…Density-dependent transition to the biofilm state A major assumption of our model is that the looselyattached community at the surface transitions to biofilm in a density-dependent manner. Following other modeling work (Moore-Ott et al, 2022;Sinclair et al, 2022), this represents a quorum-sensing mechanism, based on extensive evidence for the involvement of quorum-sensing in biofilm initiation in a variety of microorganisms (Davies et al, 1998;Hammer and Bassler, 2003;Yarwood et al, 2004;Koutsoudis et al, 2006). However, it is also clear that other, non-density-dependent signaling pathways, such as cyclic-di-GMP signaling, are also central in biofilm initiation (Valentini and Filloux, 2016).…”

Vertical growth dynamics of biofilms

“…Understanding the dynamics of this expansion, and the processes responsible for them, is fundamental to understanding biofilm development (Lambert et al, 2014;Nadell et al, 2016;Wille and Coenye, 2020). Many studies have focused on understanding the horizontal "range expansion," detailing the impact of physical interactions, the environment, inter-strain competitive dynamics, and more (D'Acunto et al, 2015;Ghosh and Levine, 2017;Wang et al, 2017;Echten et al, 2020;Fei et al, 2020;Xiong et al, 2020;Fortune et al, 2022;Tam et al, 2022;Moore-Ott et al, 2022). Conversely, less is known about the vertical growth of biofilms, despite its importance for determining access to nutrients and oxygen (De Beer et al, 1994;Stewart et al, 2016).…”

“…Understanding the dynamics of this expansion, and the processes responsible for them, is fundamental to understanding biofilm development (4)(5)(6). Many studies have focused on understanding the horizontal "range expansion," detailing the impact of physical interactions, the environment, inter-strain competitive dynamics, and more (7)(8)(9)(10)(11)(12)(13)(14)(15). Conversely, less is known about the vertical growth of biofilms, despite its importance for determining access to nutrients and oxygen (16,17).…”