Experimental evolution in biofilm populations

Steenackers, Hans; Parijs, Ilse; Dubey, Akhilesh; Foster, Kevin R.; Vanderleyden, Jozef

doi:10.1093/femsre/fuw030

Cited by 44 publications

(64 citation statements)

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“…The findings are particularly remarkable given that experiments are performed in well mixed bioreactors with continuous resource renewal, and even the highest density thresholds occur in the exponential growth regime for unperturbed populations. The surprisingly strong effect of competition under these conditions suggests that similar approaches may yield even more dramatic results in natural environments, where spatial heterogeneity and limited diffusion may enhance competition [65][66][67].…”

Section: Discussionmentioning

confidence: 99%

Antibiotics can be used to contain drug-resistant bacteria by maintaining sufficiently large sensitive populations

Hansen

Karslake

Woods

et al. 2019

Preprint

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Treatment strategies for infectious disease often aim to rapidly clear the pathogen population in hopes of minimizing the potential for antibiotic resistance. However, a number of recent studies highlight the potential of alternative strategies that attempt to inhibit the growth of resistant pathogens by maintaining a competing population of drug-sensitive cells. Unfortunately, to date there is little direct experimental evidence that drug sensitive cells can be leveraged to enhance antibiotic containment strategies. In this work, we combine in vitro experiments in computer-controlled bioreactors with simple mathematical models to show that drug-sensitive cells can enhance our ability to control bacterial populations with antibiotics. To do so, we measured the "escape time" required for drug-resistant E. coli populations to eclipse a threshold density maintained by adaptive antibiotic dosing. While populations containing only resistant cells rapidly escape containment, we found that matched populations with sensitive cells added could be contained for significantly longer. The increase in escape time occurs only when the threshold density-the acceptable bacterial burden-is sufficiently high, an effect that mathematical models attribute to increased competition. The results provide direct experimental evidence linking the presence of sensitive cells to improved control of microbial populations.

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Section: Discussionmentioning

confidence: 99%

Antibiotics can be used to contain drug-resistant bacteria by maintaining sufficiently large sensitive populations

Hansen

Karslake

Woods

et al. 2019

Preprint

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“…Experimental evolution studies continuously deepen our understanding of microbial adaptation, revealing common evolutionary scenarios such as genome reduction (Nilsson et al 2005) or genome rearrangements (Martin et al 2017), hypermutability (Flynn et al 2016;Tenaillon et al 2016), or diversification (Rainey and Travisano 1998;Poltak and Cooper 2011;Traverse et al 2013;Koch et al 2014;Flynn et al 2016;Kim, Levy and Foster 2016). The last one, where microbes diversify into distinct variants (typically referred to as morphotypes as they are identified based on distinct colony morphology), appears to be very common, especially in structured environments which offer alternative niches varying in nutrient and oxygen content (Martin et al 2016;Steenackers et al 2016). Biofilms, where microbes grow in tightly packed assemblies, represent an example of such an environment.…”

Section: Introductionmentioning

confidence: 99%

Evolution of exploitative interactions during diversification in Bacillus subtilis biofilms

Dragoš

Lakshmanan

Martin

et al. 2017

Preprint

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Microbial biofilms are tightly packed, heterogeneous structures that serve as arenas for social interactions. Studies on Gram negative models reveal that during evolution in structured environments like biofilms, isogenic populations commonly diversify into phenotypically and genetically distinct variants. These variants can settle in alternative biofilm niches and develop new types of interactions that greatly influence population productivity. Here, we explore the evolutionary diversification of pellicle biofilms of the Gram positive, spore-forming bacterium Bacillus subtilis. We discover that -similarly to other species -B. subtilis diversifies into distinct colony variants. These variants dramatically differ in biofilm formation abilities and expression of biofilm-related genes. In addition, using a quantitative approach, we reveal striking differences in surface complexity and hydrophobicity of the evolved colony types.Interestingly, one of the morphotypes completely lost the ability of independent biofilm formation and evolved to hitchhike with other morphotypes with improved biofilm forming abilities. Genome comparison suggests that major phenotypic transformations between the morphotypes can be triggered by subtle genetic differences. Our work demonstrates how positive complementarity effects and exploitative interactions intertwine during evolutionary diversification in biofilms.

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“…They range from increased ecological opportunity in a highly structured environment (Brockhurst et al 2006;Kassen 2009), to ecological interactions with the environment where the cells engineer their environment and create new niches which can then allow new morphological variations to thrive (Kassen 2009;Poltak and Cooper 2010), cheating and other forms of 'social' cell-to-cell interactions (Rainey and Rainey 2003), to increased contributions of genetic drift, mutations and clonal interference (Zhang and Buckling 2011;Gómez and Buckling 2013). The relative role of each process remains to be determined and is likely highly circumstantial (see Steenackers et al 2016 for a review).…”

Section: Schaummentioning

confidence: 99%

Enhanced biofilm formation aids adaptation to extreme warming and environmental instability in the diatom Thalassiosira pseudonana and its associated bacteria

Schaum

2018

Limnology & Oceanography

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Recent studies have highlighted the capacity of marine diatoms at the foundation of ocean food webs and biogeochemical cycles to respond to environmental change. These responses are a combination of physiological acclimation and evolutionary responses. The latter occur rapidly within a few hundred generations (translating to a scale of months to years), due to the large standing genetic variation and short generation times of diatom populations. Studies are usually carried out on diatom species in their planktonic state, but this may constitute a stark oversimplification: diatoms readily form biofilms in the water column of shallow coastal areas, where biofilm formation affects carbon export, and in the benthos, where biofilms contribute significantly to sediment stability. Here, I have carried out a 400‐generation selection experiment, where I evolved the diatom Thalassiosira pseudonana and its associated bacteria. Bacteria and diatom were cultured in their planktonic form, and under strong selection for rapid biofilm formation in temperature and nutrient regimes differing in their severity and stability. I find that biofilm formation is enhanced under mild warming and rapid thermal fluctuations but not under extreme warming regardless of nutrient availability. Evolutionary responses are slower in biofilms under benign conditions but speed up under extreme and fluctuating conditions. Taxonomic composition of the associated bacteria is driven by the temperature selection regime in biofilms but not in planktonic samples. I also show that T. pseudonana, when selected for biofilm formation, presents predictable and sequential morphologies that are not usually observed in planktonic T. pseudonana.

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Experimental evolution in biofilm populations

Cited by 44 publications

References 0 publications

Antibiotics can be used to contain drug-resistant bacteria by maintaining sufficiently large sensitive populations

Antibiotics can be used to contain drug-resistant bacteria by maintaining sufficiently large sensitive populations

Evolution of exploitative interactions during diversification in Bacillus subtilis biofilms

Enhanced biofilm formation aids adaptation to extreme warming and environmental instability in the diatom Thalassiosira pseudonana and its associated bacteria

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