title: Exploring the low-pressure growth limit: evolution of Bacillus subtilis in the laboratory to enhanced growth at 5 kilopascals.
abstract: 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.
authors.affiliation: Space Life Sciences Laboratory, Kennedy Space Center, FL 32899, USA. WLN@ufl.edu
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Nicholson
authors.forename: Patricia
authors.initials: P
authors.lastname: Fajardo-Cavazos
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Fedenko
authors.forename: José L
authors.initials: JL
authors.lastname: Ortíz-Lugo
authors.forename: Andrea
authors.initials: A
authors.lastname: Rivas-Castillo
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Waters
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Schuerger
mesh_terms: D000220:Adaptation, Biological; D001412:Bacillus subtilis / Q000254:growth & development* / Q000502:physiology; D006874:Hydrostatic Pressure; D012692:Serial Passage