Metabolite analysis of Mycobacterium species under aerobic and hypoxic conditions reveals common metabolic traits

A metabolite profiling approach has been implemented to elucidate metabolic adaptation at set culture conditions in five Mycobacterium species with the potential to act as model organisms for Mycobacterium tuberculosis (Mtb). Analysis has been performed over designated growth phases and under representative environments (nutrient and oxygen depletion) experienced by Mtb during infection. The procedure was able to determine a range of metabolites (60 - 120 compounds) covering nucleotides, amino acids, organic acids, saccharides, fatty acids, glycerols, -esters, -phosphates and isoprenoids. Among these classes of compounds key biomarker metabolites were identified that can act as indicators of pathway/process activity. In numerous cases, common metabolite traits were observed for all five species across the experimental conditions . Amino acid content, especially glutamic acid, highlighted the different properties between the fast- and slow-growing mycobacteria studied. The greatest similarities in metabolite composition between fast- and slow-growing mycobacteria were apparent under hypoxic conditions. A comparison to previously reported transcriptomic data revealed a strong correlation between changes in transcription and metabolite content. Collectively, these data validate the changes in the transcription at the metabolite level, suggesting transcription exists as one of the predominant modes of cellular regulation in Mycobacterium. Whilst, sectors with restricted correlation between metabolites and transcription (e.g. hypoxic cultivation) warrant further study to elucidate and exploit post-transcriptional modes of regulation. The strong correlation between the laboratory conditions used and data derived from in vivo conditions, indicates that the approach applied is a valuable addition to our understanding of cell regulation in these Mycobacterium species.