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Graduate Exam Abstract


Ashish Sharma

Ph.D. Final

July 1, 2008, 2:00 P.M.

Engineering B101

Analysis of differential gene in E. coli following exposure to non-thermal atmospheric-pressure plasma plume


Abstract: The suitability of non-thermal plasmas operating at atmospheric pressure for applications in surface decontamination and sterilization is an active area of research. Plasma decontamination provides a low temperature and non-toxic means of treating objects where heating and exposure to poisonous compounds is not acceptable especially in applications relating to medical devices and food packaging. The effects of various constituents of plasma (UV photons, reactive species, charged particles etc.), acting independently and in a synergistic manner, on bacteria at the biomolecular level is not well understood. It is imperative to investigate the mechanism of inactivation in order to design safe and reliable plasma devices. We used high-density oligonucleotide microarrays for exploring the differential gene expression in E. coli following plasma treatment. Microarray technology enabled the profiling of the entire genome of E. coli. The results obtained indicate a significant induction of genes involved in DNA repair and recombination suggesting that plasma exposure caused massive DNA damage in the cell. There was also evidence of oxidative stress and suppression of genes involved in housekeeping functions of energy metabolism and ion transport. Experiments were also carried out to optimize plasma operating parameters to achieve a higher rate of inactivation of microbes.

Adviser: Dr. George Collins
Co-Adviser: Dr. Amy Pruden
Non-ECE Member: Dr. Azer Yalin (Mechanical Engineering)
Member 3: Dr. H.J. Siegel
Addional Members: NA

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