scholarly journals Swimming bacteria power microspin cycles

2018 ◽  
Vol 4 (12) ◽  
pp. eaau0125 ◽  
Author(s):  
Alex E. Hamby ◽  
Dhruv K. Vig ◽  
Sasha Safonova ◽  
Charles W. Wolgemuth
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model ◽  
Cell Biophysics ◽  
Single Vortex ◽  
Morphological Alterations ◽  
Active Behavior ◽  
Dense Suspensions ◽  
Swimming Bacteria ◽  
Medium Viscosity ◽  
Stable Vortex

Dense suspensions of swimming bacteria are living fluids, an archetype of active matter. For example,Bacillus subtilisconfined within a disc-shaped region forms a persistent stable vortex that counterrotates at the periphery. Here, we examinedEscherichia coliunder similar confinement and found that these bacteria, instead, form microspin cycles: a single vortex that periodically reverses direction on time scales of seconds. Using experimental perturbations of the confinement geometry, medium viscosity, bacterial length, density, and chemotaxis pathway, we show that morphological alterations of the bacteria transition a stable vortex into a periodically reversing one. We develop a mathematical model based on single-cell biophysics that quantitatively recreates the dynamics of these vortices and predicts that density gradients power the reversals. Our results define how microbial physics drives the active behavior of dense bacterial suspensions and may allow one to engineer novel micromixers for biomedical and other microfluidic applications.

Kinetic mathematical model for ketone bioconversion using Escherichia coli TOP10 pQR239

2014 ◽  
Vol 240 ◽  
pp. 1-9 ◽  
Author(s):  
R. Melgarejo-Torres ◽  
O. Castillo-Araiza ◽  
P. López-Ordaz ◽  
D. Torres-Martínez ◽  
M. Gutiérrez-Rojas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model

scholarly journals A Wall of Funnels Concentrates Swimming Bacteria

2007 ◽  
Vol 189 (23) ◽  
pp. 8704-8707 ◽  
Author(s):  
Peter Galajda ◽  
Juan Keymer ◽  
Paul Chaikin ◽  
Robert Austin
Keyword(s):  
Escherichia Coli ◽  
Porous Media ◽  
Biological Tissue ◽  
Selection Pressure ◽  
Random Motion ◽  
Swimming Bacteria ◽  
Multistage Pump ◽  
Narrow Opening ◽  
Arbitrary Shapes ◽  
Motile Bacteria

ABSTRACT Randomly moving but self-propelled agents, such as Escherichia coli bacteria, are expected to fill a volume homogeneously. However, we show that when a population of bacteria is exposed to a microfabricated wall of funnel-shaped openings, the random motion of bacteria through the openings is rectified by tracking (trapping) of the swimming bacteria along the funnel wall. This leads to a buildup of the concentration of swimming cells on the narrow opening side of the funnel wall but no concentration of nonswimming cells. Similarly, we show that a series of such funnel walls functions as a multistage pump and can increase the concentration of motile bacteria exponentially with the number of walls. The funnel wall can be arranged along arbitrary shapes and cause the bacteria to form well-defined patterns. The funnel effect may also have implications on the transport and distribution of motile microorganisms in irregular confined environments, such as porous media, wet soil, or biological tissue, or act as a selection pressure in evolution experiments.

scholarly journals Shared Antigenic Determinants Between Spermatozoa and Bacteria: An Experimental Study

2019 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Escherichia Coli ◽  
Experimental Study ◽  
Streptococcus Pyogenes ◽  
Secretory Protein ◽  
Antigenic Determinants ◽  
Morphological Alterations ◽  
Bacterial Immobilization ◽  
Sperm Immobilization ◽  
Motile Bacteria

Sperm immobilization factor (SIF), the secretory protein of Staphylococcus aureus, is known to cause complete immobilization, death and morphological alterations in mouse spermatozoa in vitro. However, the present study aims to explore a newer dimension of SIF i.e., to bind to motile and non-motile bacteria and its ability to induce immobilization of motile bacteria in vitro. The results showed that 800µg of SIF caused complete immobilization of motile bacteria, however, death and morphological alterations could not be observed even with 1000µg of SIF. Furthermore, this SIF-mediated bacterial immobilization was reversed when each of the SIF-binding receptor from mouse spermatozoa and bacteria (Escherichia coli and Streptococcus pyogenes) was incubated with bacteria, thereby, providing an experimental evidence of similarity between the antigenic determinants present on spermatozoa and bacteria against a common ligand, SIF.

scholarly journals Molecular circuits for associative learning in single-celled organisms

2008 ◽  
Vol 6 (34) ◽  
pp. 463-469 ◽  
Author(s):  
Chrisantha T Fernando ◽  
Anthony M.L Liekens ◽  
Lewis E.H Bingle ◽  
Christian Beck ◽  
Thorsten Lenser ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model ◽  
Associative Learning ◽  
Experimental Evidence ◽  
Protein Kinases ◽  
Regulatory Network ◽  
Preliminary Design ◽  
Phosphorylated Protein ◽  
Alternative Approach ◽  
Gene Regulatory

We demonstrate how a single-celled organism could undertake associative learning. Although to date only one previous study has found experimental evidence for such learning, there is no reason in principle why it should not occur. We propose a gene regulatory network that is capable of associative learning between any pre-specified set of chemical signals, in a Hebbian manner, within a single cell. A mathematical model is developed, and simulations show a clear learned response. A preliminary design for implementing this model using plasmids within Escherichia coli is presented, along with an alternative approach, based on double-phosphorylated protein kinases.

scholarly journals Insights into mucosal innate responses to Escherichia coli O157 : H7 colonization of cattle by mathematical modelling of excretion dynamics

2011 ◽  
Vol 9 (68) ◽  
pp. 518-527 ◽  
Author(s):  
Michael J. Tildesley ◽  
David L. Gally ◽  
Tom N. McNeilly ◽  
J. Chris Low ◽  
Arvind Mahajan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model ◽  
Model Comparison ◽  
Innate Immune ◽  
Host Responses ◽  
Post Inoculation ◽  
Model Based ◽  
Complex Interactions ◽  
Bacterial Replication

Mathematical model-based statistical inference applied to within-host dynamics of infectious diseases can help dissect complex interactions between hosts and microbes. This work has applied advances in model-based inference to understand colonization of cattle by enterohaemorrhagic Escherichia coli O157 : H7 at the terminal rectum. A mathematical model was developed based on niche replication and transition rates at this site. A nested-model comparison, applied to excretion curves from 25 calves, was used to reduce complexity while maintaining integrity. We conclude that, 5–9 days post inoculation, the innate immune response negates bacterial replication on the epithelium and either reduces attachment to or increases detachment from the epithelium of the terminal rectum. Thus, we provide a broadly applicable model that gives novel insights into bacterial replication rates in vivo and the timing and impact of host responses.

scholarly journals Phenotypic Tolerance: Antibiotic Enrichment of Noninherited Resistance in Bacterial Populations

2005 ◽  
Vol 49 (4) ◽  
pp. 1483-1494 ◽  
Author(s):  
C. Wiuff ◽  
R. M. Zappala ◽  
R. R. Regoes ◽  
K. N. Garner ◽  
F. Baquero ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Antibiotic Treatment ◽  
A Priori ◽  
The Other ◽  
Bacterial Populations ◽  
Microbiological Outcome

ABSTRACT When growing bacteria are exposed to bactericidal concentrations of antibiotics, the sensitivity of the bacteria to the antibiotic commonly decreases with time, and substantial fractions of the bacteria survive. Using Escherichia coli CAB1 and antibiotics of five different classes (ampicillin, ciprofloxacin, rifampin, streptomycin, and tetracycline), we examine the details of this phenomenon and, with the aid of mathematical models, develop and explore the properties and predictions of three hypotheses that can account for this phenomenon: (i) antibiotic decay, (ii) inherited resistance, and (iii) phenotypic tolerance. Our experiments cause us to reject the first two hypotheses and provide evidence that this phenomenon can be accounted for by the antibiotic-mediated enrichment of subpopulations physiologically tolerant to but genetically susceptible to these antibiotics, phenotypic tolerance. We demonstrate that tolerant subpopulations generated by exposure to one concentration of an antibiotic are also tolerant to higher concentrations of the same antibiotic and can be tolerant to antibiotics of the other four types. Using a mathematical model, we explore the effects of phenotypic tolerance to the microbiological outcome of antibiotic treatment and demonstrate, a priori, that it can have a profound effect on the rate of clearance of the bacteria and under some conditions can prevent clearance that would be achieved in the absence of tolerance.

scholarly journals Heterogeneous Absorption of Antimicrobial Peptide LL37 inEscherichia coliCells Enhances Population Survivability

2018 ◽  
Author(s):  
Mehdi Snoussi ◽  
John Paul Talledo ◽  
Nathan-Alexander Del Rosario ◽  
Bae-Yeun Ha ◽  
Andrej Košmrlj ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model ◽  
Minimum Inhibitory Concentration ◽  
Cell Density ◽  
Inhibitory Concentration ◽  
Single Cell Level ◽  
Cell Level ◽  
E Coli ◽  
Rapid Absorption ◽  
Growing Population

AbstractAntimicrobial peptides (AMPs) are broad spectrum antibiotics that selectively target bacteria. Here we investigate the activity of human AMP LL37 againstEscherichia coliby integrating quantitative, population and single-cell level experiments with theoretical modeling. Our data indicate an unexpected, rapid absorption and retention of a large number of LL37 byE. colicells upon the inhibition of their growth, which increases the chance of survival for the rest of population. Cultures with high-enough cell density exhibit two distinct subpopulations: a non-growing population that absorb peptides and a growing population that survive owing to the sequestration of the AMPs by others. A mathematical model based on this binary picture reproduces the rather surprising behaviors ofE. colicultures in the presence of LL37, including the increase of the minimum inhibitory concentration with cell density (even in dilute cultures) and the extensive lag in growth introduced by sub-lethal dosages of LL37.

scholarly journals Antithetic population response to antibiotics in a polybacterial community

2020 ◽  
Vol 6 (10) ◽  
pp. eaaz5108 ◽  
Author(s):  
L. Galera-Laporta ◽  
J. Garcia-Ojalvo
Keyword(s):  
Escherichia Coli ◽  
Mathematical Model ◽  
Bacillus Subtilis ◽  
Bacterial Species ◽  
Single Species ◽  
Population Response ◽  
E Coli ◽  
Collective Response ◽  
Lactam Antibiotic ◽  
Mixed Community

Much is known about the effects of antibiotics on isolated bacterial species, but their influence on polybacterial communities is less understood. Here, we study the joint response of a mixed community of nonresistant Bacillus subtilis and Escherichia coli bacteria to moderate concentrations of the β-lactam antibiotic ampicillin. We show that when the two organisms coexist, their population response to the antibiotic is opposite to that in isolation: Whereas in monoculture B. subtilis is tolerant and E. coli is sensitive to ampicillin, in coculture it is E. coli who can proliferate in the presence of the antibiotic, while B. subtilis cannot. This antithetic behavior is predicted by a mathematical model constrained only by the responses of the two species in isolation. Our results thus show that the collective response of mixed bacterial ecosystems to antibiotics can run counter to what single-species potency studies tell us about their efficacy.

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