This proposed research program is directed towards development of a novel sensor prototype utilizing whole cells for the dosimetry monitoring of harmful solar radiation levels and for the detection of volatile organic compounds indicative of biohazardous microbial biomass.
The sensor prototype consists of genetically engineered bioluminescent bioreporter microorganisms interfaced with an integrated circuit, hence the designation bioluminescent bioreporter integrated circuits, or BBICs. The bioreporters are engineered to bioluminescence when a target analyte is encountered while the integrated circuit is designed to detect the bioluminescence, process the signal, and communicate the result, either remotely or through a direct interface with a control system network. This technology offers several advantages instrumental to NASA-related applications. BBIC mass, size, and power requirements are minimal, and, since they are completely self- contained units, crew time is not required in the preparation of sensors for deployment. System reliability is confirmed through the utilization of redundant sensors, and BBICs will be adaptable to long-term storage requirements. We have performed proof-of-concept studies to develop prototype BBICs proficient at detecting detrimental environmental contaminants in concentrations approaching 10 parts-per-billion. This proposed research effort will concentrate on the expansion of BBIC technology to produce bioluminescent bioreporters capable of dosimetry monitoring of potentially harmful, biologically active ultraviolet light exposure and detection of volatile organic compounds as early signature indicators of biohazardous microbial contamination events in spacecraft or planetary-based habitats.
A bacterial strain capable of sensing the MVOC para-cymene was chosen as a proof-of-concept biosensor for detection of microbial contamination. The genetic construction methodology for developing this bioreporter involved isolation of the promoter region of the para-cymene regulatory gene cymB utilizing PCR. The cymB promoter was cloned in front of the promoterless luxCDABE genes from Vibrio fischeri in a mini-Tn5 artificial transposon which was then introduced into Pseudomonas putida F1, using kanamycin as a selective agent. Exposure of resulting clones to varying concentrations of para-cymene yielded bioluminescent responses. The mini-Tn5 artificial transposon was similarly utilized to construct a bioreporter sensitive to UV light. For spacecraft applications, size, power consumption, and cable plant concerns are the dominant issues for BBICs. Therefore, the integrated circuit portion of the BBIC should reside on a single chip, be compatible with battery operation, and allow for flexible communications with central data collection stations in addition to allowing the integration of high-quality photodiodes and low-noise analog signal processing. We chose a standard 0.5-um bulk CMOS process that meets optical and signal processing requirements, and provides for the size and power attributes described above. The complete microluminometer chip measures 2.2 mm x 2.2 mm with the photodetector occupying ~ 25% of the total chip area. Preliminary results indicate that bioluminescent bioreporters can be successfully created for MVOC and UV detection, with emphasis now being directed towards interfacing the bioreporters with the integrated circuit. Once accomplished, this technology will offer several advantages instrumental to NASA-related applications. BBIC mass, size, and power requirements are minimal, and, since they are completely self-contained units, crew time is not required in the preparation of sensors for deployment.
<p>Additionally, system reliability is confirmed through the utilization of redundant sensors, and BBICs remain adaptable to long-term storage requirements.
As the BBIC represents wholly new technology, it inherently possesses a broad range of novel applications for industrial, public healhealth, military, and agricultural purposes. The BBIC prototype proposed for MVOC detection can be used for air quality estimation (with respect to fungal count) in a variety of enclosed spaces such as commercial/residential buildings, automobiles, and air handling ducts. BBICs could also be configured such that on sensing a fungal count above an allowable limit, the sensor response could trigger a biocide releasing mechanism or turn on air cleaning equipment. The proposed version of the BBIC prototype as a radiation dosimeter could be integrated with the space suit, such that astronauts could be forewarned of excess cosmic radiation during Extra Vehicular Activities. For Earth-based implementation, the rapid measurement of harmful biologically effective UV dose exposures has near limitless applications, from the monitoring of commercial pilots during high-altitude flights to the monitoring of increased UV-B radiation effects on terrestrial and aquatic plant, animal, and microbial life.