(134e) Effects of Low Dose Ionizing Radiation on Microorganisms for Creating Inconspicuous Biosentinels

Traditional radiation detection systems are extremely sensitive to low doses of ionizing radiation, however the disadvantages of being easily identifiable, mandatory placement near a radioactive source for detection, and capacity to report radioactivity at a specific moment in time diminish their applications in the field. Given the current state of world affairs, there is a need for an inconspicuous sensor capable of unattended autonomous operation for reporting radioactivity even if the source has been relocated. A set of transcriptional based biosensors capable of discerning radionuclide type have the potential to monitor and report on nuclear fuel cycle, enrichment, and weapon development activities in diverse environmental conditions. Transcriptional responses of model and environmental microorganisms exposed to acute and chronic alpha, beta, gamma and neutron radiations are analyzed through RNA sequencing to identify unique radiation-induced signatures. After quantitative PCR verification, these unique signatures could be used to engineer a set of microbial transcriptional based biosensors. Our work with Pseudomonas putida and Escherichia coli indicate key differences in gene expression after acute and chronic exposure to Plutonium 239 at a dose rate of 8.6 mGy/d. Substantial differences in differentially expressed genes were noted between acute and chronic exposures of P. putida indicating the potential presence of a radiation-induced time signature. Unique upregulated genes from each organism and time point will be engineered into initial toehold switch biosensor prototypes. Furthermore, changes in oxidative stress response were measured even due to low dose radiation exposure, suggesting one possible mechanism for radiation response. The results of this work will expand upon the limited knowledge of low level radiation effects in microorganisms and lead to passive and autonomous monitoring of clandestine nuclear activities.