Researchers at NASA’s Jet Propulsion Laboratory (JPL), Pasadena,
Calif., have demonstrated a prototype device that automatically and
continuously monitors the air for the presence of bacterial spores. The
result is a novel alarm capability reminiscent of smoke detectors.
Current methods for detecting bacterial spores, such as anthrax,
require a trained operator. The large number of trained monitors
required, and associated costs, limits widespread implementation of
these methods.
“Having a technician continuously monitor the air for spores is like
having the fire department live at your house to ensure there is no
fire,” said Dr. Adrian Ponce, a chemist and senior member of the
technical staff at JPL. “What you want is a smoke detector, a device
that continuously monitors the air for smoke, or in our case, bacterial
spores,” he said.
Ponce co-author of a paper titled, “An Anthrax ‘Smoke’ Detector: Online
Monitoring of Aerosolized Bacterial Spores” which recently appeared in
Engineering in Medicine and Biology magazine, published by the
Institute of Electrical and Electronics Engineering. The paper details
recent tests to detect airborne bacterial spores.
In a related development, JPL recently entered into an agreement with
Universal Detection Technology (UDT), Beverly Hills, Calif., a public
company specializing in environmental monitoring technologies. The
agreement, to mutually develop a commercially available anthrax ‘smoke’
detector, will combine JPL spore detection technology with Universal’s
aerosol capture device. The partnership with UDT is possible through
the Technology Affiliates Program, one of many Commercial Technology
Programs aimed at transferring JPL knowledge to the private sector to
improve public quality of life.
Ponce and Elizabeth D. Lester, a senior in microbiology at Baylor
University, Waco, Texas, performed the tests on the anthrax detector
last summer. Their paper details test results
using harmless Bacillus subtilis spores that were aerosolized to
simulate an anthrax attack. Bacillus subtilis is found worldwide in
soils and on root vegetables.
During the tests, aerosolized spores were captured with an aerosol
sampler and suspended in a solution. Suspended spores were ruptured
with microwaves to release a chemical from inside the spores called
dipicolinic acid, which is unique to bacterial spores. This dipicolinic
acid instantaneously reacts with the chemical sensor in the solution.
The sensor triggers an intense green luminescence when viewed under
ultraviolet light. The intensity of the luminescence corresponds to
the concentration of bacterial spores in the sample.
If an increase in spore concentration is detected, an alarm sounds. A
technician would respond to confirm the presence of anthrax spores
using traditional sampling and analysis, such as colony counting and
polymerase chain reaction, which amplifies DNA to measurable
concentrations. The instrument response time is 15 minutes, fast
enough to help prevent widespread contamination.
JPL’s bacterial spore detection system is simple and robust, a
prerequisite for continuous monitoring. The system is designed for
constant and unattended monitoring of spaces such as public
facilities and commercial buildings. Two features of the device
prevent false alarms. JPL’s detection technology discriminates
against detecting aerosol components, such as dust, and the device
only sounds an alarm when it detects a significant increase in spore
count.
The system used by UDT cannot distinguish between inorganic particles
or biological substances such as bacterial spores. For the next 12
months, JPL will work to incorporate bacterial spore detection
technology to make the device sensitive enough for use by Universal
as a bioterrorism warning monitor.
JPL initially became involved in monitoring bacterial spores to
quantify the concentration of spores in spacecraft assembly
facilities. These are the facilities where spacecraft are built and
housed before missions. NASA has a planetary protection policy
regulating biological contamination control for all spacecraft. Under
this policy, JPL researchers must take precautions against
accidentally transferring microbes to other planets. This experience
gives JPL researchers unique capabilities to perform work in
detecting microorganisms.
The California Institute of Technology manages JPL for NASA.
