Sterilization of Esherichia coli and the microorganisms of turmeric samples with corona discharge plasma

A low cost corona gun plasma system that works at atmospheric pressure and operates with high voltage power supply was tested for its biocidal effect on Escherichia coli bacteria as Gram-negative bacteria and different microorganisms of commercial turmeric (curcuma longa) as a combination of both Gram-negative and Gram-positive bacteria and results are compared. In these experiments, the Escherichia coli bacteria with a population of 4.4×?10?^7 cfu/ml were perfectly sterilized after 5 seconds irradiation of plasma generated by the corona gun, while it took about 80 s for sterilizing the microorganisms of turmeric samples. Results show that, with increasing the discharge energy and plasma exposure time, the rate of sterilization increases. Their survival curves are straight lines with two slopes for Gram-negative bacteria and three slopes for microorganisms in turmeric.