Life of Escherichia coli under photooxidative stress at different pH

Escherichia coli, commonly known as coli bacillus, is one of the enteric bacteria species living in the large intestine of mammals. In Escherichia coli, genes involved in the cellular response to environmental stress (acid shock, base shock, starvation stress, osmotic stress, oxidative stress and DNA damage) are expressed. Among these genes, arginine decarboxylase name, glutamate decarboxylase gad and lysine decarboxylase cad are known as acid resistance system. In this study, Escherichia coli BW25113 strains obtained from keio collection were transferred to wild type Escherichia coli W3110 for target 6 gene region using P1kc phage transduction method. The role of methylene blue and pH stress of mutants adiA, gadB, gadC, cadA, cadB, cadC obtained from wild type Escherichia coli W3110 was investigated. In addition, the roles of complements of genes in stress conditions were controlled by plasmids obtained by the same method. Survival experiments on wild type and mutant strains were carried out at 2 different pH (pH-6 and pH-8), by colony counting method on petri plates. No sensitivity was observed in wild-type and mutant strains in pH-6 phosphate buffer, but it was observed to be effective only in pH-8 phosphate buffer. It was determined that in all strains containing pH 8 methylene blue, there was 2 logarithmic decrease at the end of 8 hours, but the maximum decrease was seen in the adiA mutant, the initial value of 6.59 logarithm decreased to 2.25 after 6 hours, and the t99 value was calculated as 2.76 hours. The lifetimes were determined from cadA>gadC>cadC>gadB>cadB>adiA mutants from best to lowest. While it was observed that methylene blue was not effective in pH 6 phosphate buffer, it was found to be effective in wild type and all gene regions in pH 8 phosphate buffer medium. These results show that adiA, gadB, cadB and cadC mutants are associated with pH stress and methylene blue.