Jonathan A. Eisen edited Results_and_Discussion_Growth_experiments__.md  about 8 years ago

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In this experiment, _Bacillus safensis_ grew to a final density of ~60% higher in space than on the ground, with very little variation between replicates (Figure 1). The genome sequence of this strain, _Bacillus safensis_ JPL-MERTA-8-2 has just been published \cite{26586895} and may contain clues as to why this strain behaved so differently in space.  It is perhaps no surprise that most built environment-associated bacteria behave very similarly on the ISS as on earth. After all, the ISS is a home and office of sorts, with environmental conditions very similar to a building on earth with the exception of gravity. The ISS is maintained at around 22 °C with a relative humidity of around 60% and pressure and oxygen concentrations very close to those at sea level on earth. Additionally, this experiment didn't did not  provide enough time to study the long-term adaptation of bacteria to the environment on board the ISS. A related project from our lab has examined the microbial community already present on the ISS \cite{12345678}. Given that the ISS appears to harbor similar microbes to built environments on earth, we also asked if there were close relatives to our 48 bacteria already present on the ISS. The vast majority (39/48) of our bacterial species were found in the existing microbial community data which is not surprising given the built environment origins of the isolates. This suggests that our data showing these species growing with similar kinetics on space and on earth is potentially relevant to the biology of the microbial communities already present on the ISS.