Growth inhibition of Escherichia coli by dichloromethane in cells expressing dichloromethane dehalogenase/glutathione S-transferase.
Dichloromethane (DCM) dehalogenase converts DCM to formaldehyde via the formation of glutathione metabolites and generates 2 mol HCl per mol DCM metabolized. Growth of Escherichia coli expressing DCM dehalogenase was immediately and severely inhibited during conversion of 0.3 mM DCM. Intracellular pH (pH(i)) rapidly decreased and chloride ions were steadily released into the medium. Bacterial growth resumed after completion of DCM conversion and cell viability was unaffected. At 0.6 mM DCM there was no recovery from growth inhibition in liquid culture due to the build-up of inhibitory concentrations of formaldehyde. DCM turnover stimulated potassium efflux from cells, which was suppressed by glucose. The potassium efflux, therefore, did not contribute to growth inhibition. It was concluded that initial growth inhibition results from lowering of the cytoplasmic pH, but severity of growth inhibition was greater than expected for the change in pH(i). Possible contributors to growth inhibition are discussed.
Evans
Gareth J
GJ
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK1.
Ferguson
Gail P
GP
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK1.
Booth
Ian R
IR
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK1.
Vuilleumier
Stéphane
S
Institut für Mikrobiologie, ETH Zürich, ETH-Zentrum/LFV, CH-8092 Zürich, Switzerland2.
D002455:Cell Division / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D008752:Methylene Chloride / Q000378:metabolism / Q000494:pharmacology*
D002712:Chlorides; D008752:Methylene Chloride; D005982:Glutathione Transferase; D008190:Lyases; C045224:dichloromethane dehalogenase