Battling bacterial biofilms with gas discharge plasma

Abstract

Most studies dealing with growth and physiology of bacteria have been carried out using free-living cells. However, most bacteria live in communities referred to as biofilms where cooperative interactions among their members make conventional methods of controlling microbial growth often ineffective. The use of gas discharge plasmas represents an alternative to traditional decontamination/sterilization methods. We studied biofilms using two organisms, Chromobacterium violaceum and Pseudomonas aeruginosa. With the first organism we demonstrated almost complete loss of cell culturability after a 5-min plasma treatment. However, additional determinations showed that non-culturable cells were still alive after short exposure times. We have recently reported the effect of plasma on P. aeruginosa biofilms grown on borosilicate coupons. In this paper, we present results for plasma treatments of 1-, 3-, and 7-day old P. aeruginosa biofilms grown on polycarbonate or stainless-steel coupons. Results indicate nearly 100% of -biofilm inactivation after 5 min of exposure with similar inactivation kinetics for 1-, 3-, and 7-day-old biofilms, and for both materials used. The inactivation kinetics is similar for both organisms, suggesting that the method is useful regardless of the type of biofilm. AFM images show changes in biofilm structure for various plasma exposure times. © 2012 Springer Science+Business Media B.V.