<p>This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</p> <p>We sought to test the hypothesis that mutant bacterial strains could be discriminated from each other on the basis of the metabolites they secrete into the medium (their
‘metabolic footprint’), using two methods of ‘global’ metabolite analysis (FT–IR and
direct injection electrospray mass spectrometry). The biological system used was
based on a published study of <italic>Escherichia coli</italic> tryptophan mutants that had been
analysed and discriminated by Yanofsky and colleagues using transcriptome analysis.
Wild-type strains supplemented with tryptophan or analogues could be discriminated
from controls using FT–IR of 24 h broths, as could each of the mutant strains in both
minimal and supplemented media. Direct injection electrospray mass spectrometry
with unit mass resolution could also be used to discriminate the strains from each
other, and had the advantage that the discrimination required the use of just two
or three masses in each case. These were determined via a genetic algorithm. Both
methods are rapid, reagentless, reproducible and cheap, and might beneficially be
extended to the analysis of gene knockout libraries.</p>
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Comp Funct Genomics. 2003 Jul; 4(4):376-391