METABOLIC CHANGES IN MYCOBACTERIUM TUBERCULOSIS DURING NUTRIENT STARVATION CONDITIONS

Abstract

Latent Mycobacterium tuberculosis exhibits metabolic pathways different from normal bacilli. Mycobacteria undergo metabolic shift leading to alteration in expression of vital cell proteins like catalase, urease etc., during nutrient starvation conditions. In this study, we determined the activity of catalase and urease in nutrient starved cultures. It was observed that catalase activity declines to 87% and 91%, when compared to log phase cultures as determined by bubble height and spectrophotometric methods, respectively. On the contrary, urease activity increases 18 fold in 42 h nutrient starved mycobacteria as compared log phase bacilli. Latency in nutrient starved bacilli was confirmed by respiration test and sensitivity tests. We also studied the susceptibility of latent bacilli to RNI under nutrient starvation conditions. Bacilli become resistant to acidified sodium nitrite induced RNI (at 0.05, 0.5, 1 µg/ml concentrations) in latency induced by nutrient starvation. Latency in nutrient starved bacilli was confirmed by respiration test and sensitivity tests. These findings suggest that changes in levels of catalase, urease and RNI susceptibility may play critical role in latent TB.