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INTRODUCTION Previous research has shown that after prolong exposure to a disinfectant, E. coli K12 can become totally resistant to that disinfectant (Hartley 2001). This ongoing research is trying to determine how E. coli K12 develops resistance to the common household disinfectant, Formula 409®. Methodology Isolation of resistant cells were accomplished by constant exposure of the cells to the disinfectant. The more resistant cells, the cell growing closest to the disinfectant or growing in dilution, were selected for culture. After repeated exposure, resistant cells were able to grow in very high dilutions of disinfectant. Possible mechanisms Some type of genetic alteration is occurring during the selection process because the cells are become more resistant. We don't know for sure what type of alteration is occurring, but we have some candidates. An attractive possibility is the multiple antibiotic resistance (MAR) system. MAR is well-studied system of transcriptional regulation of antibiotic resistance conferring genes. Activation of the mar operon in turn causes the activation of a set of operons in E. coli and other bacteria. These gene products allow cells to respond to the presence of antibiotics or disinfectants (Martin et al., 1995, Rosner et al., 1994). Because of its multiple effects on the cell, the mar system is termed a regulon. The mar regulon is particularly interesting because many of the genes in it are also induced by oxidative stress. Mar regulation (see Fig. 10) occurs via positive transcriptional regulation of genes in the regulon, including inaA, fumC, micF, rpsfF, sodA, zwf and additional unidentified genes (Anderson, 1999).
Approximate Word count = 944
Approximate Pages = 3.8
(250 words per page double spaced)
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