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

Abstract

E xperiments were conducted on an aqueous growth medium containing cultures of Escherichia c oli ( 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 bacteria l culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii ) shock compression followed by spray . T he apparatus allow s the generati on of a n adjustable lo a ding shock wave of magnitude up to 3 00 M Pa in a sterile laboratory environment. C ultures of E. coli were tested with this apparatus and the s pread - plate technique was used to measure the survivability after mechanical loading . T he loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compressi on . We present results of preliminary experi ments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilise large volumes of fluid samples.