Figure 3From: Measurement of microbial activity in soil by colorimetric observation of in situ dye reduction: an approach to detection of extraterrestrial lifeReduction of DCIP dye by the heat-treated control soil and the extraterrestrial surrogate soil (Idaho red sand) Data points represent: (■), autoclaved (killed) control soil; (▲), live soil; (●) blank, no soil. Data points are means of 3 replicates. Error bars represent +/- standard deviation. Dye-only controls showed no reduction over the time course of the experiment. AU = Absorbance UnitsBack to article page