METABOLIC-ACTIVITY OF MICROORGANISMS IN EVAPORITES

Crystalline salt is generally considered so hostile to most forms of l ife that it has been used for centuries as a preservative. Here, we pr esent evidence that prokaryotes inhabiting a natural evaporite crust o f halite and gypsum are metabolically active while inside the evaporit e for at least 10 months. In situ measurements demonstrated that some of these ''endoevaporitic'' microorganisms (probably the cyanobacteriu m Synechococcus Nageli) fixed carbon and nitrogen. Denitrification was not observed. Our results quantified the stow microbial activity that can occur in salt crystals. Implications of this study include the po ssibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.