Hi to you all,
I am testing the mode of action of a new antibacterial agent against MRSA and when I came to the gene expression part, I found that the MurG and MurB gene expression are increased significantly when I expose the bacterial cells to 8xMIC value for 20 hours, comparing to the control ( no treatment applied). However, the cfu decreased significantly comparing to the control ( check by turbidity). On the other hand, when I treat the bacterial cell with the same concentration (8xMIC) but only for 4 hours incubation the gene expression of MurG and MurB decreased and the Cfu decreased too (check by turbidity).
These two genes are playing important roles in peptidoglycan synthesis, subsequently the cell wall synthesis. Basically, deactivating or any disruption of gene expression of MurG and MurB will affect the cell wall synthesis process and lead to fatal changes in the cell wall which drive the bacterial cell to death.
So, How to explain this phenomena and what is the logical explanation for the gene expression results ? any help or suggestions ?
Regards,
P.S: I have repeat the experiment three times.
I think some antibacterial agents cause site directed inhibition of gene(s) or markers linked to growth and the gene expression of MurG and MurB is probably independent from these growth factors (genes) which are most likely affected these sites more than others such as MurG and MurB genes
There is many factors can be considered so it's hard to give you a straight answer.
Why you use 8 folds MIC? What's your purpose?
When you give such a stress to bacteria many systems turned on and many others turn off but we usually use this type of stress (8 folds MIC and 4 h treatment) to produce presister cells.
Maybe check the systems involved in be helpful.
Regards
I think some antibacterial agents cause site directed inhibition of gene(s) or markers linked to growth and the gene expression of MurG and MurB is probably independent from these growth factors (genes) which are most likely affected these sites more than others such as MurG and MurB genes
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