A multiphase theory for spreading microbial swarms and films

Srinivasan, Siddarth; Kaplan, C. Nadir; Mahadevan, L.

doi:10.7554/elife.42697

Cited by 55 publications

(70 citation statements)

References 54 publications

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“…The copyright holder for this preprint this version posted October 26, 2020. ; https://doi.org/10.1101/2020.10.26.355560 doi: bioRxiv preprint RFP strain requires growth in a matrix-capable biofilm. A recent study showed that biofilm colony expansion in three dimensions depends heavily on extracellular matrix, while two-dimensional growth relies more on cell growth and division [43]. To test whether the mutualism between alrA and the matrix-deficient parent was dependent on three-dimensional growth, we grew co-cultures between an agar pad and a coverslip.…”

Section: Wild-type Cells Rescue Alra Knockdown In a Biofilm Colony Bymentioning

confidence: 99%

Three-dimensional biofilm growth supports a mutualism involving matrix and nutrient sharing

Arjes

Willis

Gui

et al. 2020

Preprint

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Life in a three-dimensional structure such as a biofilm is typical for many bacteria, yet little is known about how strains with different genotypes interact in this context. Here, to systematically explore gene knockdowns across various three-dimensional contexts, we created arrayed libraries of essential-gene CRISPRi knockdowns in the model biofilm-forming bacterium Bacillus subtilis and measured competitive fitness during colony co-culture with a wild type-like parent on different media and at different knockdown levels. Partial knockdown led to a wide range of fitness phenotypes, with targeting of translation-related genes often leading to lower growth rates and rapid out-competition by the parent. Several knockdowns competed differentially in biofilms versus non-biofilm colonies, in some cases due to lack of a particular nutrient in one medium. Cells depleted for the alanine racemase AlrA died in monoculture, but co-cultures survived via nutrient sharing in a biofilm but not in liquid. This rescue was enhanced in biofilm co-culture with a parent unable to produce extracellular matrix, due to a mutualism involving nutrient and matrix sharing. Including alrA, we identified several examples of mutualism involving matrix sharing that occurred in a three-dimensional biofilm colony but not when growth was constrained to two dimensions. These findings demonstrate that growth in a three-dimensional biofilm can promote genetic diversity through sharing of secreted factors, and illustrate the role of matrix production in determining trajectories for biofilm evolution that may be relevant to pathogens and other environmental bacteria.

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Section: Wild-type Cells Rescue Alra Knockdown In a Biofilm Colony Bymentioning

confidence: 99%

Three-dimensional biofilm growth supports a mutualism involving matrix and nutrient sharing

Arjes

Willis

Gui

et al. 2020

Preprint

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“…Paenibacillus dendritiformis [7] form dendritic protrusions, which can develop into highly branched structures. Bacillus subtilis [17,23] and pseudomonas [15,[24][25][26][27] have been shown to expand in either smooth fronts or dendritic patterns dependent on various chemical and physical factors. We and others have shown, for instance, that by simply varying the agar concentrations [15,26], adding external surfactants into the agar [15], or simply leaving the agar surface to dry for some time [15], the patterns of the colonies or swarms can vary from smooth to dendritic edges.…”

Section: Introductionmentioning

confidence: 99%

An expanding bacterial colony forms a depletion zone with growing droplets

Tang

Bell

2020

Preprint

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Many species of bacteria have developed means to spread on solid surfaces. This study focuses on the expansion of Pseudomonas aeruginosa on an agar gel surface. We report the occurrence and spread of a depletion zone, where the layer of bacteria on the agar becoming thinner. The depletion zone occurs within an expanded colony under conditions of minimal water evaporation. It is colocalized with a higher concentration of rhamnolipids, the biosurfactants that are produced by the bacteria and accumulate in the older region of the colony. With continued growth in bacterial population, dense droplets occur and coalesce in the depletion zone, displaying remarkable fluid dynamic behavior. Whereas expansion of a central depletion zone requires activities of live bacteria, new zones can be seeded by adding rhamnolipids. These depletion zones due to the added surfactants expand quickly, even on plates covered by bacteria that have been killed by ultraviolet light. We propose a model to account for the observed properties, taking into consideration bacterial growth and secretion, osmotic swelling, fluid volume expansion, cell-cell interaction, and interfacial fluid dynamics involving Marangoni flow.

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“…For example, it may not be possible to predict from growing each species by itself what the joint reproductive output of a collective will be, or how robust such a collective will be to external biotic and abiotic perturbations. Microbial communities can also perform chemical transformations that would be impossible for one individual species to achieve [18], and some communities even display complex behaviours such as collective motion and electrochemical signalling, which have traditionally been associated with higher organisms [19,20].…”

mentioning

confidence: 99%