Microbial cells stained green. This picture shows many tiny cells in which DNA is abundantly included inside the cells. First, the microbial cells were detected in fractures in the rock sample using an infrared imaging technique called O-PTIR spectroscopy. After that, they were stained with a green solution and analyzed using both a scanning electron microscope and then fluorescent microscopy. The combination of readings from these three imaging techniques enabled the researchers to confirm the indigenous and living microbial cells in the 2-billion-year-old rock fissure.
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