A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray

Abstract

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

On the Generation of an Intense Temperature Gradient Through a Modified Shock Tube Hydrodynamics for a Possible Continuous Sterilization Process

“…Likewise, Shock tubes can be used typically to study fluid dynamics under a wide range of temperatures and pressures that are difficult to achieve experimentally as in combustion and disintegration reactions [2] where the shock tube has been used in a double diaphragm conception. More recently, they have been used in biomedical research and bioengineering to study for example how bacteria are affected by shock waves [3], in vitro processing [4], and in composite materials [5]. Many other shock tube applications can be found in chemical kinetics as the tube ignition delay time measurements for methyl propanoate and methyl acrylate that of combustion fuels exhibiting negative temperature coefficient where shock tube can serve to estimate ignition delay times [6], sprays where resonance gas oscillations cause vigorous aerosol deposition leading to a rapid concentration decrease [7], and spectroscopy where shock-tube experiments are investigated for thermal decomposition of biochemicals [8].…”