Authors

Discussion

Metabolic foot printing involves quantification of metabolite uptake and excretion from the culture media. Use of chemically defined media for metabolic foot printing brings new insights into nutrients utilisation, determination of growth dependent changes of cellular metabolism and standardisation of results between laboratories. In our study, time resolved metabolic foot printing was carried out by comparison of culture supernatant of L.mexicana promastigotes at various time points and extensive bioinformatics analysis was carried out to derive significant biological information. Of the 205 metabolites putatively identified across replicates in both positive and negative ionisation mode, 68 metabolites matched with authentic standards for individual mass/charge ratio and retention time comparison. Overall, ~25 % metabolites depleted from the medium, ~15% not changed significantly and ~40% of metabolites significantly enriched in the medium. Glucose, adenosine and certain amino acids were amongst the depleted components of the medium compared to vitamins from the defined medium composition. Furthermore, amino acids such as L-tryptophan, L-aspartate, L-glutamate, L-arginine, L-methionine and L-serine were classified under continuous utilisation as more than half the initial abundance were consumed from the medium in 9 days growth period. Amino acids such as L-leucine, L-threonine, L-valine, L-phenylalanine, L-tyrosine and L-lysine were taken up moderately. L-Glycine, L-glutamine, L-asparagine, L-proline and L-alanine were significantly enriched in medium over time.  Systematic analysis of the 40% excreted small molecules enriched in the culture media allowed new insights about their role in establishment of parasitism, with macrophage cells as in vitro experimental model.