INVESTIGATION OF THE ROLE OF RpoS IN Escherichia coli AGAINST METALS AND pH STRESSES

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RpoS (σ38), which acts as an alternative sigma factor in Escherichia coli, controls the expression of genes responsible for cellular responses to different stresses including acidity, starvation, osmotic, oxidative stress, DNA damage, and stationary phase transition. In this study, the role of the rpoS gene in E. coli W3110 under metals and pH stresses was investigated. The rpoS gene, which is a mutant in the E. coli BW25113 strain, was transferred by transduction with the P1kc phage to wild-type E. coli W3110. Life experiments in wild-type E. coli W3110 and rpoS mutant E. coli W3110 strains were carried out by plate counting method at 3 different pH, in pH 5,5, 7,0 and 8,5 phosphate buffer. The role of rpoS in the presence of 6 different metals (Zn, Ni, Co, Cd, Ag and Cu) was also determined by minimum inhibition concenration (MIC) and drop plate method. Sensitivity in rpoS mutant strains was observed at all pH values studied. It was determined that the rpoS mutant E. coli against cadmium metal showed resistance, but there was no role in other metals. Verification of the role of the rpoS gene was achieved by genetic complementation. These results show that the RpoS alternative sigma factor plays a role in the control of genes related to cadmium metal and in the genes associated with pH stress.

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Escherichia coli , rpoS , Metal stress , Cadmium

Anadolu University Journal of Science and Technology C - Life Sciences and Biotechnology

121

Anadolu University Journal of Science and Technology C - Life Sciences and Biotechnology