Effects of cell surface loading and phase of growth in cold atmospheric gas plasma inactivation of Escherichia coli K12
Article first published online: 17 JUL 2006
Journal of Applied Microbiology
Volume 101, Issue 6, pages 1323–1330, December 2006
How to Cite
Yu, H., Perni, S., Shi, J.J., Wang, D.Z., Kong, M.G. and Shama, G. (2006), Effects of cell surface loading and phase of growth in cold atmospheric gas plasma inactivation of Escherichia coli K12. Journal of Applied Microbiology, 101: 1323–1330. doi: 10.1111/j.1365-2672.2006.03033.x
- Issue published online: 17 JUL 2006
- Article first published online: 17 JUL 2006
- 2005/1364: received 15 November 2005, revised and accepted 17 March 2006
- Escherichia coli;
- inactivation model;
- nonthermal gas plasma;
- phase of growth;
- surface cell concentration
Aims: To determine the effects of surface cell concentration and phase of growth on the inactivation of Escherichia coli cells using an atmospheric nonthermal plasma.
Methods and Results: Cells of E. coli K12 were deposited onto the surface of membrane filters and exposed to the plume from a cold atmospheric gas plasma. Scanning electron microscopy revealed severe loss in structural integrity of plasma-treated cells, and optical emission spectra indicated that inactivation was brought about by reactive plasma species. The survival of E. coli cells was found to depend on the cell surface density: as the surface density increased from 107 to 1011 CFU cm−2, the rate constant in the Baranyi inactivation model decreased from 19·59 to 1·03 min−1. Cells harvested from mid-exponential, late exponential and stationary phases of growth displayed differences in their resistances to the effects of the plasma however, exponential phase cells were not more susceptible than those from the stationary phase.
Conclusions: High surface concentrations of cells affects the penetration of plasma species and treatment effectiveness. The physiological state of cells, as determined by phase of growth, affects their resistance to plasma inactivation.
Significance and Impact of the Study: In designing inactivation treatments, surface concentration and cell physiology need to be taken into account.