The role of the outer membrane in formaldehyde tolerance in Escherichia coli VU3695 and Halomonas sp. MAC.
To investigate the mechanism of formaldehyde tolerance in Gram-negative bacteria, two formaldehyde-tolerant strains, Escherichia coli VU3695 and Halomonas sp. MAC (DSM 7328), and formaldehyde-sensitive revertants obtained by ethidium bromide or novobiocin treatment were studied. The presence of high levels of formaldehyde dehydrogenase activity alone proved insufficient to confer tolerance to high formaldehyde concentrations, as shown by high activity displayed by formaldehyde-sensitive revertants of Halomonas MAC. Moreover, formaldehyde-tolerant strains also proved to be tolerant to high concentrations of acetaldehyde and glutaraldehyde, which are not oxidized by formaldehyde dehydrogenase. Treatment with sublethal concentrations of EDTA rendered the resistant strains highly sensitive to formaldehyde without affecting the activity of formaldehyde dehydrogenase. Comparison of the outer membrane proteins of formaldehyde-resistant strains with those of their sensitive revertants showed the presence of at least one additional high molecular mass protein in the tolerant strains. It is concluded that formaldehyde tolerance in the bacteria studied depends on the composition and structure of the outer membrane.
Azachi
Malkit
M
Department of Plant Pathology and Microbiology, and Otto Warburg Center for Biotechnology in Agriculture, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Henis
Yigal
Y
Department of Plant Pathology and Microbiology, and Otto Warburg Center for Biotechnology in Agriculture, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Shapira
Roni
R
Department of Biochemistry and Food Science, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Oren
Aharon
A
Division of Microbial and Molecular Ecology, Institute of Life Sciences and Moshe Shilo Center for Marine Biogeochemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
D000079:Acetaldehyde / Q000494:pharmacology; D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005557:Formaldehyde / Q000494:pharmacology*; D005976:Glutaral / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D016296:Mutagenesis
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D005557:Formaldehyde; C020145:formaldehyde dehydrogenase (glutathione); D000445:Aldehyde Oxidoreductases; D000079:Acetaldehyde; D005976:Glutaral