In VitroGene Expression Dissected: Chemostat Surgery forMycobacterium tuberculosis

Abstract

A unique approach, combining defined and reproduciblein vitromodels with DNA microarrays, has been developed to study environmental modulation of mycobacterial gene expression. The gene expression profiles of samples ofMycobacterium tuberculosis, from independent chemostat cultures grown under defined and reproducible conditions, were found to be highly correlated. This approach is now being used to study the effect of relevant stimuli, such as limited oxygen availability, on mycobacterial gene expression. A modification of the chemostat culture system, enabling largevolume controlled batch culture, has been developed to study starvation survival. Cultures ofM. tuberculosishave been maintained under nutrient-starved conditions for extended periods, with106–107bacilli surviving in a culturable state after 100 days. The design of the culture system has made it possible to control the environment and collect multiple time-course samples to study patterns of gene expression. These studies demonstrate that it is possible to perform long-term studies and obtain reproducible expression data using controlled and definedin vitromodels.