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Related Experiment Video

Updated: Apr 12, 2026

A Microfluidic Device for Quantifying Bacterial Chemotaxis in Stable Concentration Gradients

A Microfluidic Device for Quantifying Bacterial Chemotaxis in Stable Concentration Gradients

Published on: April 20, 2010

A novel directly coupled gradostat.

J W Wimpenny¹, R G Earnshaw, H Gest

¹Department of Pure and Applied Biology, University of Wales, College of Cardiff, UK.

Journal of Microbiological Methods

|October 1, 1992

Summary

A simplified diffusion-coupled (DC) gradostat establishes chemical gradients for microbial studies. This compact apparatus successfully separated bacterial species with different salt sensitivities and monitored methylotroph viability in a methanol gradient.

Keywords:

NASA Discipline Exobiology NASA Discipline Number 52-30 Non-NASA Center

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Last Updated: Apr 12, 2026

A Microfluidic Device for Quantifying Bacterial Chemotaxis in Stable Concentration Gradients

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Design and Use of Multiplexed Chemostat Arrays

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Published on: February 23, 2013

Area of Science:

Microbiology
Biotechnology
Chemical Engineering

Background:

The original bidirectional compound chemostat (gradostat) is a complex apparatus for establishing chemical gradients.
A need exists for a more compact and simplified system to study microbial responses in controlled chemical environments.

Purpose of the Study:

To simplify the bidirectional compound chemostat (gradostat) into a more compact diffusion-coupled (DC) gradostat.
To demonstrate the efficacy of the DC gradostat in separating microbial species and assessing microbial viability under gradient conditions.

Main Methods:

Designed a compact five-chamber apparatus where chemical gradients are established via diffusion.
Incorporated turbines for agitation within each chamber on a common horizontal shaft.
Utilized two distinct biological experiments to validate the DC gradostat's performance.

Main Results:

Observed expected changes in cell viability of Methylophilus methylotrophus along a methanol gradient.
Successfully separated two species of photosynthetic bacteria (Rhodobacter capsulata and Rhodopseudomonas marina/agilis) with differing salt sensitivities.
Demonstrated effective separation using a 0-3% NaCl gradient.

Conclusions:

The diffusion-coupled (DC) gradostat is a simplified and effective tool for creating and maintaining chemical gradients.
The DC gradostat can be used to study microbial physiology, such as cell viability.
This apparatus facilitates the separation of microbial species based on their differential responses to environmental gradients.