Electrochemical cell lysis of gram-positive and gram-negative bacteria: DNA extraction from environmental water samples

Abstract

Cell lysis is an essential step for the nucleic acid-based surveillance of bacteriol. water quality. Recently, electrochem. cell lysis (ECL), which is based on the local generation of hydroxide at a cathode surface, has been reported to be a rapid and reagent free-method for cell lysis. Herein, we describe the development of a rapid, high throughput ECL device and its performance characterization with respect to the DNA extn. potential for gram-neg. bacteria Escherichia coli, Salmonella Typhi and Enterobacter cloacaeand gram-pos. bacteria Enterococcus faecalisand Bacillus subtilis. Both gram-neg. and gram-pos. bacteria were lysed within 1 min of ECL at 40 mA (with a voltage of ~5 V) obtaining DNA extn. efficiencies of ~80% and ~20% relative to the conventional bead beating method, resp. The ECL system outperformed homogeneous chem. lysis in terms of reaction times and DNA extn. efficiencies due in part to the high pH generated at the cathode surface, which was predicted by simulations of the hydroxide transport in the cathodic chamber. The ECL method described herein is demonstrated to be applicable to various environmental water sample types including turtle pond water, untreated wastewater, and treated wastewater with relative DNA extn. efficiencies varying from 62% to 71%. These results indicate that the ECL method of DNA extn. has demonstrable potential for rapid, simplified and low-cost sample prepn. as a prelude to PCR analyses of microbes in environmental water samples.