Non-replicative persistence of M. tuberculosis under iron starvation

Iron restriction is a growth limiting condition encountered by M. tuberculosis in the host. In this study we examined the survival and physiology of iron depleted M. tuberculosis. We found that iron depleted M. tuberculosis survive for long time with little or no replication and is able to resume normal growth when iron becomes available. To understand the mechanism used by M. tuberculosis to survive under iron starvation we examine the transcriptional profile of iron-starving in comparison to that of iron-sufficient M. tuberculosis. M. tuberculosis was depleted of exogenous iron and pressed to use stored iron(Fe) at which point cells stop growing but remained viable for long time. Total RNA of iron depletion adapted Mtb (IDAM) at 1 day, 1 week and 2 weeks after cells have entered growth arrest was extracted and transcripts compared to those of cells subjected to Fe-depletion but then supplemented with Fe 24hr before RNA extraction. These cells are referred to as iron sufficient mycobacterium (ISM)