FIG 2.

Survival of the tested microorganisms in the stratospheric balloon flights. The tested parameters were desiccation resistance (ground sample), desiccation plus exposure to high-altitude environment but without UV exposure (flight nonexposed), and desiccation plus full exposure to high-altitude environment (flight exposed). (A) Survival of the microorganisms with the first balloon flight, performed in May 2016. (B) Survival of the microorganisms with the second balloon flight, performed in February 2018. Error bars represent the standard deviation between three distinct spots. **, only one spot of B. subtilis spores was recovered from the exposed assay of the first flight; *, no CFU observed for exposed H. watticus on both balloon flights.