AN INQUIRY INTO MICROORGANISMS CONTAINED IN ENHYDRO AGATE WATER: A GEOCHEMICAL AND GEOMICROBIOLOGICAL STUDY

Enhydro agates are obloid-shaped nodules composed of banded microcrystalline to cryptocrystalline quartz that have an internal cavity filled with water. Agate material precipitates from silica-rich groundwater that percolates through volcanic rock and forms concentric layers inside vesicles. As layers develop, portions of the groundwater from which the agate precipitates can become trapped within an internal cavity, thus preserving a volume of ancient water inside the agate. Enhydro agates utilized in this study are from the Providence of Rio Grande de Sol, Brazil, and are estimated to have begun forming about 60 to 40 million years ago. Heated groundwater involved in hydrothermal alteration of volcanic rocks typically contains microorganisms and we hypothesize that microorganisms may become trapped inside enhydro agates as they form. Moreover, we hypothesize that these microorganisms are most likely thermophilic and chemolithotrophic in nature. Samples of agate water were obtained by aseptically drilling into the internal cavity and extracting the water for analyses. This ongoing research aims to investigate both geochemical and geomicrobiological characteristics of enhydro agates and the possible existence of ancient microorganisms entrapped in the water.

Preliminary supporting evidence for our hypotheses was obtained through direct microscopic examination of sample water. Wet mounts prepared following water extraction from several agates revealed cell-like shapes including small (~ 1 μm) diplococcoid, coccobacillus, and bacillus forms that displayed erratic movement consistent with bacterial motility and not Brownian movement. Further evidence including attempted enrichment procedures will employ basic and epifluorescent stains to detect specific cellular components. Initial nucleic acid extractions revealed low concentrations of genetic material from several agate water samples.

Chemical analyses using the scanning electron microscope (SEM) with energy dispersive x-ray (EDX) spectrometer indicate that accessory minerals inside the agates are black needles that vary in composition from manganite (MnO(OH)) to psilomelane ((Ba,H2O)2Mn5O10). Enrichment media were developed based on geochemical data obtained from SEM analyses and results of these studies will be presented.