METABOLIC ACTIVITY OF MICROORGANISMS IN EVAPORITES1

Abstract
Crystalline salt is generally considered so hostile to most forms of life that it has been used for centuries as a preservative. Here, we present evidence that prokaryotes inhabiting a natural evaporite crust of halite and gypsum are metabolically active while inside the evaporite for at least 10 months.In situmeasurements demonstrated that some of these “endoevaporitic” microorganisms (probably the cyanobacteriumSynechococcusNägeli) fixed carbon and nitrogen. Denitrifecation was not observed. Our results quantified the slow microbial activity that can occur in salt crystals. Implications of this study include the possibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.