1. Developing a microfluidic device for in situ water column
profiling of phototrophic sulfur bacteria
Abstract
Phototrophic purple sulfur bacteria are crucial to study in
Biogeochemistry because they are thought to be one of the first
organisms to utilize inorganic material and light in an anoxic
environment to utilize photosynthesis. Often these bacteria are
found in aquatic conditions in anoxic lakes. These kinds of lakes
can be found in northern Indiana and the Pacific Northwest. To
study these bacterial and the environmental conditions in which
they thrive, one needs to locate and extract them from their
native habitat. The bacteria are found in a specific region of the
water column and are difficult to locate. On top of this, these
bacteria also live among other microscopic organisms. To
address this we have designed and constructed a device that
detects and extracts samples of purple sulfur bacteria from a
specific position in the water column in anoxic lakes. The purple
sulfur bacteria’s light absorbance and fluorescence properties
were tested under laboratory conditions. That information was
then used to develop the design for light detection scheme. In
addition, thermal sensors were incorporated in the device to
determine the temperature range of the sulfur bacteria’s
environment. We will present the current circuit design and how
it is utilized in the detection of purple sulfur bacteria. Discussion
of the future work on developing an apparatus for data collection
will be presented. We hope to show the apparatus design and
how the device may be utilized across various platforms and
applications.
Materials
Current Status of Research
• The Apparatus and electronics have been
designed and assembled
• The control box and user interface display are
currently being optimized
• The seals on the compartments will be tested
• The device is currently pending trials in the field
Introduction
References
1. Serra, Teresa, et al., “Evaluation of Laser in Situ
Scattering Instrument For Measuring Concentration
of Phytoplankton, Purple Sulfur Bacteria, and
Suspended
Inorganic Sediments in Lakes.” Journal of
Environmental Engineering, 2001.
2. Hubas, Cedric et al., “Tool providing new insight
into coastal anoxygenic purple bacterial mats.
Review and perspectives.” Institut Pasteur, 2011.
Zachary East1, Austin Kellogg1, Horia I. Petrache1, Bruce D. Ray1, William P. Gilhooly III2, and
Merrell A. Johnson1
1Department of Physics and 2Department of Earth Sciences Indiana University Purdue
University Indianapolis, Indianapolis, IN 46202
Apparatus
Design
- Sample of purple sulfur bacteria.
- Conceptual design.
Control
board
Light
Detection
User
Interface
Power
Supply
Environmental
sensors
• Phototrophic purple sulfur bacteria existing within the
water column of anoxic lakes are believed to provide
insight into the Early Earth.
• Extracting these specimens, however, proves to be a
great challenge in the field.
• In order to solve this problem, an apparatus with specific
light and temperature sensing components was designed
and optimized for testing in the field.
Prototype
- Picture of constructed prototype. (Side View)
- Picture of constructed prototype. (Top-Down View)
- Diagram of Prototype Design
- Control circuit board prototype
- Mask and copper lad material
Delerin was used to construct the platforms,
the battery enclosure, light detection
compartments and the top half of the circuitry
enclosure.
Aluminum was used to construct the circuitry
platform, and the temperature and ambient
light detection platform.