Effect of pressure waves on bacteria suspended in water

Abstract

SummaryShock pressure vaves with a frequency of 50/sec. and a maximal pressure of 60-70 kg./cm.2 greatly reduced the viability of E. coli. A similar effect was ottained also on staphylococci, enterococci, Salmonelfa Zanzibar, and coliphnges T.. On the contrary no effect on spores of B. sttbtilzs was found. The effect was practically independent of the maximal pressure within the range from 30-80 kg./cm.2, the highest pressure tested. The effect decreased with increasing cell density of the bacterial suspension. Bacteria surviving shock treatment died considerably more rapidly when stored at 4°C. than bacteria treated in the same way except for exposure to pressure waves. Morphological examinations with the aid of ordinary Ii&t microscopy as well as electron microscopy suggest that the effect was due to mechanical action on the bacterial cell n-alls.

Neutralization of Bacterial Aerosols by Aerodynamic Shocks in a Novel Impactor System: An Integrated Computational and Experimental Study

“…show any significant effect on B. subtilis spores [40]. The authors also demonstrated that an increase in concentrations results in an increase of bacterial viability.…”

“…The shock can be applied at the point of release both in indoor and outdoor air with the advantage of avoiding chemicals. Some experimental data exist in the literature [25,40,56] on the use of shock waves to neutralize bacteria; however, these studies are limited to bacterial liquid suspensions or powders and do not assess the effects of a shock in the aerosol phase. We aim at understanding the fate of the bioaerosol particles when exposed to shocks of different velocity, temperature and pressure gradients in air.…”

“…Although detailed data for the effect of shocks on bioaerosol particles are lacking, aerodynamic shocks have been shown to cause lysis of bacteria suspended in the liquid phase [40,56]. Teshima et al (1995) [56] studied the biomechanical effects on E. coll by attaching a test tube with the bacterial suspension at the end of a shock tube.…”

“…In earlier studies, Lundbeck et al (1963) [40] used a shock peak pressure of « 6 MPa with variable number of pulses to neutralize bacteria suspended in the liquid phase.…”

“…In previous liquid suspension shock studies, it has been shown that an increase in cell concentration results in an increase in bacterial viability [40]. The controlled bacterial nebulization process produces individual cells suspended in air that can pass isolated through the shock, thereby avoiding the concentration effect seen in liquid suspension studies.…”