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Flocks of birds, schools of fish and herds of animals are all good examples of collective migration, where individuals co-ordinate their behavior to improve survival. This process also happens on a cellular level; for example, when bacteria consume a nutrient in their surroundings, they will collectively move to an area with a higher concentration of food via a process known as chemotaxis. Several studies have examined how disturbing collective migration can cause populations to fall apart. However, little is known about how groups withstand these interferences. To investigate, Bhattacharjee, Amchin, Alert et al. studied bacteria called Escherichia coli as they moved through a gel towards nutrients. The E. coli were injected into the gel using a three-dimensional printer, which deposited the bacteria into a wiggly shape that forces the cells apart, making it harder for them to move as a collective group. However, as the bacteria migrated through the gel, they smoothed out the line and gradually made it straighter so they could continue to travel together over longer distances. Computer simulations revealed that this smoothing process is achieved by differences in how the cells respond to local nutrient levels based on their position. Bacteria towards the front of the group are exposed to more nutrients, causing them to become oversaturated and respond less effectively to the nutrient gradient. As a result, they move more slowly, allowing the cells behind them to eventually catch-up. These findings reveal a general mechanism in which limitations in how individuals sense and respond to an external signal (in this case local nutrient concentrations) allows them to continue migrating together. This mechanism may apply to other systems that migrate via chemotaxis, as well as groups whose movement is directed by different external factors, such as temperature and light intensity.
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Sonification of Chemotactic Waves of Bacteria
Chemotaxis is the ability of certain microscopic organisms to sense and swim towards beneficial or away from detrimental chemicals in their surroundings. Identifying this behavior is important for understanding the relationships between species and their environments in the natural world. Predicting migration of an entire population from known characteristics of individual microorganisms is a key contribution, but can be a laborious process and requires watching and waiting for visual evidence of the process on a large population scale. Sonification offers a novel solution to this problem by allowing the observer to tap into our auditory sensory system to process information. In this project, we developed and assessed a proof-of-concept sonification tool as a high throughput, real-time screening tool for chemotaxis in populations of swimming bacteria. The tool operates by reporting the y-axis position of bacteria that appear in the microscope image as microsecond duration pitched notes, giving the user a sense of the average location of the population. In this paper, we present how it has been used as a chemotaxis assay and as a tool to locate traveling waves of bacteria as they pass through the field of view in order to capture data at specific timepoints, which is used to analyze individual swimming patterns of microorganisms within the wave.
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- Award ID(s):
- 1950369
- PAR ID:
- 10535282
- Publisher / Repository:
- International Community for Auditory Display
- Date Published:
- ISBN:
- 0-9670904-9-0
- Page Range / eLocation ID:
- 106 to 112
- Format(s):
- Medium: X
- Location:
- Linköping University
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.21785/icad2023.8263
