[Back to Number 5 ToC] [Back to Journal Contents] [Back to Biokhimiya Home page]

Effects of Penetrating and Non-penetrating Oxidants on Escherichia coli

G. V. Smirnova,1 N. G. Muzyka,1 M. N. Glukhovchenko,1 and O. N. Oktyabrsky1,2

1Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, ul. Goleva 13, Perm, 614081 Russia; fax: (3422) 64-67-11; E-mail: mike@iegm.perm.su

2To whom correspondence should be addressed.

Submitted March 29, 1996; revision submitted January 6, 1997.
Treatment of Escherichia coli K-12 cells aerobically grown in M9 glucose salt medium with penetrating (H2O2) and non-penetrating (ferricyanide) oxidants resulted in similar inhibition of growth and decrease in intracellular K+ pool by 15%. Only H2O2 inhibited growth of auxotrophic strains grown in M9 medium supplemented with protein hydrolysate. Ferricyanide reduction was associated with decrease in low-molecular-weight thiols, whereas the treatment of cells with H2O2 increased their level. Pretreatment of cells with ferricyanide enhanced the H2O2-induced expression of katG gene encoding for catalase HPI; this gene is a member of the gene family controlled by the oxyR gene. Pretreatment with ferricyanide inhibited H2O2-induced expression of the sfiA gene which is the a member of the gene family controlled by the recA and lexA genes. Glutathione is the major low-molecular-weight thiol in E. coli, and it can play different roles in cellular responses to H2O2 and ferricyanide.
KEY WORDS: Escherichia coli, oxidant, thiol, potassium, gene expression.