Preservation of microorganisms within halite fluid inclusions from the Salar de Uyuni, Bolivia

A 220m core from Salar de Uyuni, Bolivia, acquired in 1999, ranges in age from 10.98+/-0.055ka (6.9m) to 276+/-21ka (116.5m). Halite was examined for microbes preserved within fluid inclusions which occur throughout the core. Optical criteria used to identify microbes were established using modern in situ (halite fluid inclusions) and in vivo (saline brine) samples from Saline Valley, California, collected in 2004. Halite crystals with potentially viable microorganisms in fluid inclusions from the core were surface sterilized and cultured in a variety of nutrient media. Two of 964 experiments achieved growth, which were subjected to DNA isolation, amplification via the Polymerase Chain Reaction, and sequencing. One episode of growth (UC13-15.9m) had nonreplicable, positive PCR results; the other (UC18-18.2m) was a staphylococcus contaminant. It was not determined if the lack of success in culturing microorganisms from halite fluid inclusions was sample-related (organism viability) or method-related (nutrient and temperature conditions).