The effect of self-generated hypoxia on the expression of target genes coding for electron transport related products in mycobacterium tuberculosis.

Abstract

The work presented here aims at identifying whether the genes identified in the genome of Mycobacterium tuberculosis that code for products involved in anaerobic metabolism are active or inactivated genes. The study consists of three distinct parts. In part one, serial dilutions of sputum of patients with pulmonary tuberculosis (PTB) were grown on agar surface and in high columns of un-agitated broth. The highest dilution from which mycobacteria was grown was for all patients significantly higher in the broth cultures than on the plates suggesting the presence of anaerobically metabolizing mycobacteria in the lungs of patients with PTB. Part two of the study identified gene expression by measuring the concentration of transcripts for 5 genes involved in aerobic or anaerobic pathways. This was done over a period of 15 weeks using un-agitated broth cultures (the Wayne method). Undulating patterns of gene expression were found with the genes coding for anaerobic metabolic pathway components expressed at higher levels than those coding for aerobic pathway components while the cultures grew older. Part three aimed at measuring transcription products of the same set of genes directly in sputum specimens. Although quantitation at bacterial cell level in the sputum could not be achieved, expression of all genes was established with on average larger quantities of transcripts of genes coding for the anaerobic pathway components.