Prospecting for microbes: Microbial imprint in terrestrial basalts with implications in the search for past and present life on Mars.

摘要

Examination of two terrestrial desert basalt samples from the San Francisco Volcanic Field in Arizona has been conducted in order to find and document evidence of microbial life. Remnants of organic material are suspected within three channels of a 900,000 year-old pedogenic sample and microorganisms were found inside fractured rock chips of a younger, 900 year-old subaerial sample. Within these chips, rods and cocci morphologies are attached to minerals via substantial amounts of biofilm material. The cells also display various life stages including cell division, lysis and desiccation. Scanning electron microscopy, electron microprobe and confocal microscopy with fluorescence staining were utilized for this task and proved to be effective biosignature tools. Also, a novel technique involving iridium-coated, fluorescence-stained samples was evaluated and shown to work. Results from this study suggest the hot endolithic environment may be a suitable model in the search for life on Mars.