Title

A diffusion-based gradient microfluidic device for the study of the cyanobacterial chemotaxis

Poster Number

5

Lead Author Affiliation

University of the Pacific

Lead Author Status

Masters Student

Second Author Affiliation

University of the Pacific

Second Author Status

Faculty

Introduction

Chemotaxis is a process in which bacteria moves in response to a chemical gradient. There is limited understanding of cyanobacterial chemotaxis in natural and artificial plant associations. A microfluidic device provides a platform to observe the mobility of cyanobacteria under highly controlled chemical and fluidic environments. Traditional microfluidic chemotaxis devices often use a steady-flow to create a chemical gradient which is problematic in studying motile bacteria, because the coupling of fluid flow and chemical concentration makes it difficult to distinguish the cause of movement. Instead, we use a diffusion-based gradient microfluidic device that consists of a three-channel microfluidic chip made of agarose in this study.

Purpose

A linear chemical gradient is established by diffusing a chemical through an agarose layer sandwiched between a PDMS buffer. This creates a static linear gradient and eliminates the flow in the center channel, allowing movement of bacteria solely by chemotaxis. The procedure for the fabrication of the microfluidic device is highlighted for future work on chemotaxis studies of other motile bacteria.

Method

The master for the microfluidic device was created using a craft-cutter. The center channel had a width of 800 um, while the buffer and and chemical channel had a width of 400 um. Soft lithography was used to create a 1mm thick PDMS buffer. After a day of cooling, a rectangle was cut off from the PDMS buffer to create space for the agarose. The 3% agarose was poured into the rectangle and allowed to cool for 2 hours. After cooling, the PDMS agarose membrane was sandwiched between a cover plexiglass cover. Gel loading tips were used to connect the inlets and outlets with the tubings.

Results

Using this device, the chemo-attraction in Nostoc strains 8964:3 towards the extracts of host and non-host plants is studied.

Significance

This study can increase the understanding of cyanobacterial chemotaxis in natural and artificial plant associations. Moreover, the protocol for the fabrication of the device can be used to fabricate more microfluidic devices for motile bacterial chemotaxis.

Location

DUC Ballroom A&B

Format

Poster Presentation

Poster Session

Afternoon

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Apr 29th, 1:00 PM Apr 29th, 3:00 PM

A diffusion-based gradient microfluidic device for the study of the cyanobacterial chemotaxis

DUC Ballroom A&B

Chemotaxis is a process in which bacteria moves in response to a chemical gradient. There is limited understanding of cyanobacterial chemotaxis in natural and artificial plant associations. A microfluidic device provides a platform to observe the mobility of cyanobacteria under highly controlled chemical and fluidic environments. Traditional microfluidic chemotaxis devices often use a steady-flow to create a chemical gradient which is problematic in studying motile bacteria, because the coupling of fluid flow and chemical concentration makes it difficult to distinguish the cause of movement. Instead, we use a diffusion-based gradient microfluidic device that consists of a three-channel microfluidic chip made of agarose in this study.