A mathematical model for Escherichia coli chemotaxis to competing stimuli

Biotech & Bioengineering

2022

Self Cite

In natural systems bacteria are exposed to many chemical stimulants; some attract chemotactic bacteria as they promote survival, while others repel bacteria because they inhibit survival. When faced with a mixture of chemoeffectors, it is not obvious which direction the population will migrate. Predicting this direction requires an understanding of how bacteria process information about their surroundings. We used a multiscale mathematical model to relate molecular level details of their twocomponent signaling system to the probability that an individual cell changes its swimming direction to the chemotactic velocity of a bacterial population. We used a microfluidic device designed to maintain a constant chemical gradient to compare model predictions to experimental observations. We obtained parameter values for the multiscale model of Escherichia coli chemotaxis to individual stimuli, α-methylaspartate and nickel ion, separately. Then without any additional fitting parameters, we predicted bacteria response to chemoeffector mixtures. Migration of E. coli toward α-methylaspartate was modulated by adding increasing concentrations of nickel ion. Thus, the migration direction was controlled by the relative concentrations of competing chemoeffectors in a predictable way. This study demonstrated the utility of a multiscale model to predict the migration direction of bacteria in the presence of competing chemoeffectors.

{K}_{{dA}}

value.…”

Section: Resultssupporting

confidence: 92%

Section: Experimental Methodsmentioning

confidence: 99%

“…Then, to evaluate chemotaxis in the presence of chemoeffectors, we used the governing equation for bacteria concentration b under steady‐state conditions

0={\mu }_{0}\frac{{\partial }^{2}b}{\partial {x}^{2}}-\frac{\partial }{\partial x}({V}_{c}b),

where

{V}_{c}

is the chemotactic velocity as derived in Middlebrooks et al (2021) for multiple chemoeffectors. Details of the derivation are provided in Online Supporting Information.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…where V c is the chemotactic velocity as derived in Middlebrooks et al (2021) for multiple chemoeffectors. Details of the derivation are provided in Online Supporting Information.…”

Section: Bacteria Transport Processes At the Population Levelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Escherichia coli chemotaxis to competing stimuli in a microfluidic device with a constant gradient

Biotech & Bioengineering

2022

Self Cite

Escherichia coli chemotaxis to competing stimuli in a microfluidic device with a constant gradient

2022

Preprint

Self Cite

In natural systems bacteria are exposed to many chemical stimulants; some attract chemotactic bacteria as they promote survival, while others repel bacteria because they inhibit survival. When faced with a mixture of chemoeffectors, it is not obvious which direction the population will migrate. Predicting this direction requires an understanding of how bacteria process information about their surroundings. We used a multiscale mathematical model to relate molecular level details of their two-component signaling system to the probability that an individual cell changes its swimming direction to the chemotactic velocity of a bacterial population. We used a microfluidic device designed to maintain a constant chemical gradient to compare model predictions to experimental observations. We obtained parameter values for the multiscale model of Escherichia coli chemotaxis to individual stimuli, α-methylaspartate and nickel ion, separately. Then without any additional fitting parameters, we predicted the response to chemoeffector mixtures. Migration of E. coli toward α-methylaspartate was modulated by adding increasing concentrations of nickel ion. Thus, the migration direction was controlled by the relative concentrations of competing chemoeffectors in a predictable way. This study demonstrated the utility of a multiscale model to predict the migration direction of bacteria in the presence of competing chemoeffectors.

Marine Bacteria Chemotaxis to Crude Oil Components with Opposing Effects

2022

Preprint

Self Cite

Marine microorganisms were critical to hydrocarbon removal from the Gulf of Mexico oil spill. Chemotaxis, a process attracting motile bacteria toward higher hydrocarbon concentrations, can increase biodegradation efficiency. However, crude oil also contains heavy metal ions that repel bacteria. Will bacteria migrate toward hydrocarbons or away from heavy metals? We exposed a marine isolate Halomonas sp. to decane and copper ions in a microfluidic device that maintained a constant concentration gradient across a channel. Bacterial distributions were used to quantify parameters in a mathematical model capturing bacteria motility and chemotaxis. This multi-scale model was adapted from the signal transduction mechanism of E. coli. For Halomonas sp., we used independent receptors for sensing attractant or repellent and chemotaxis parameter values were assessed. Predictions based on the multi-scale model correctly estimated the net attraction or repulsion responses of bacteria to the stimuli mixture. In some cases, the model yielded a stronger repulsion than what was observed experimentally, but still captured the general trends of bacteria distribution. Understanding how marine bacteria integrate information from multiple inputs to yield net migration toward or away from oil will improve predictions of hydrocarbon degradation rates.