"Breathprint" Analysis of Microbial Communities

A technique for assessing changes in the densities and compositions of communities of microorganisms in environmental samples is based partly on redox chemistry. Suspensions of microbes from environmental samples are inoculated into 95-well microtiter plates. Each well contains an initially colorless redox-sensitive dye and a source of carbon different from the sources of carbon in the other wells. If the microorganisms in a well can utilize or degrade the source of carbon, then the colorless dye is reduced to a colored crystal. The overall pattern of color in the various wells can be regarded as a "breathprint" of the microbial community. Because inoculation of the wells takes less than a minute and the reading of colors and analysis of the resulting data are largely automated, an assay by this technique can be performed relatively quickly. The technique has been used for such diverse purposes as monitoring the stability of microbial populations in artificial plant-growth and life-support systems, testing for toxicity, monitoring bioremediation, monitoring industrial bioreactors, studying subsurface microbiology, and studying fertility of agricultural soils.