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. Oktyabrsky^1,2

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.

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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.

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KEY WORDS: Escherichia coli, oxidant, thiol, potassium, gene expression.

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