Exploring the low-pressure growth limit: evolution of Bacillus subtilis in the laboratory to enhanced growth at 5 kilopascals.
Growth of Bacillus subtilis cells, normally adapted at Earth-normal atmospheric pressure (∼101.3 kPa), was progressively inhibited by lowering of pressure in liquid LB medium until growth essentially ceased at 2.5 kPa. Growth inhibition was immediately reversible upon return to 101.3 kPa, albeit at a slower rate. A population of B. subtilis cells was cultivated at the near-inhibitory pressure of 5 kPa for 1,000 generations, where a stepwise increase in growth was observed, as measured by the turbidity of 24-h cultures. An isolate from the 1,000-generation population was obtained that showed an increase in fitness at 5 kPa when compared to the ancestral strain or a strain obtained from a parallel population that evolved for 1,000 generations at 101.3 kPa. The results from this preliminary study have implications for understanding the ability of terrestrial microbes to grow in low-pressure environments such as Mars.
Nicholson
Wayne L
WL
Space Life Sciences Laboratory, Kennedy Space Center, FL 32899, USA. WLN@ufl.edu
Fajardo-Cavazos
Patricia
P
Fedenko
Jeffrey
J
Ortíz-Lugo
José L
JL
Rivas-Castillo
Andrea
A
Waters
Samantha M
SM
Schuerger
Andrew C
AC
D000220:Adaptation, Biological; D001412:Bacillus subtilis / Q000254:growth & development* / Q000502:physiology; D006874:Hydrostatic Pressure; D012692:Serial Passage