Long-term manipulations of intact microbial mat communities in a greenhouse collaboratory: simulating earth's present and past field environments.
Photosynthetic microbial mat communities were obtained from marine hypersaline saltern ponds, maintained in a greenhouse facility, and examined for the effects of salinity variations. Because these microbial mats are considered to be useful analogs of ancient marine communities, they offer insights about evolutionary events during the >3 billion year time interval wherein mats co-evolved with Earth's lithosphere and atmosphere. Although photosynthetic mats can be highly dynamic and exhibit extremely high activity, the mats in the present study have been maintained for >1 year with relatively minor changes. The major groups of microorganisms, as assayed using microscopic, genetic, and biomarker methodologies, are essentially the same as those in the original field samples. Field and greenhouse mats were similar with respect to rates of exchange of oxygen and dissolved inorganic carbon across the mat-water interface, both during the day and at night. Field and greenhouse mats exhibited similar rates of efflux of methane and hydrogen. Manipulations of salinity in the water overlying the mats produced changes in the community that strongly resemble those observed in the field. A collaboratory testbed and an array of automated features are being developed to support remote scientific experimentation with the assistance of intelligent software agents. This facility will permit teams of investigators the opportunity to explore ancient environmental conditions that are rare or absent today but that might have influenced the early evolution of these photosynthetic ecosystems.
Bebout
Brad M
BM
Exobiology Branch, NASA Ames Research Center, Moffett Field, California 94035, USA. Brad.M.Bebout@nasa.gov
Carpenter
Steven P
SP
Des Marais
David J
DJ
Discipulo
Mykell
M
Embaye
Tsegereda
T
Garcia-Pichel
Ferran
F
Hoehler
Tori M
TM
Hogan
Mary
M
Jahnke
Linda L
LL
Keller
Richard M
RM
Miller
Scott R
SR
Prufert-Bebout
Leslie E
LE
Raleigh
Chris
C
Rothrock
Michael
M
Turk
Kendra
K
D000458:Cyanobacteria / Q000254:growth & development*; D018534:Earth, Planet; D004777:Environment; D004780:Environment, Controlled; D006859:Hydrogen / Q000032:analysis; D008386:Marine Biology; D008697:Methane / Q000032:analysis; D008839:Microelectrodes; D008954:Models, Biological; D010100:Oxygen / Q000032:analysis
D006859:Hydrogen; D008697:Methane; D010100:Oxygen