Emphasis on *may:*
In short, bacteria, algae and other simple organisms were trapped in brine which eventually was encases within halite (“rock salt”) in Australia 830 million years ago, back when a few algal cells clumping together was the height of complexity. These simple organisms are of course dried out… but that drying may (*MAY*) have preserved them stably enough that some might (*MGHT*) be revivable.
It is a valid question: “Ummm… should we be reviving critters what been dead nearly a billion years?” One argument would be “sure, what the hell,” because we’ve had 830 million years to evolve way past any threat they might pose. The other point of view is “Have you never watched any science fiction?!?!” and assume that 830 million years may well have evolved us so far away from them that there’s essentially no link, and no remaining understanding of how to combat them.
Quoting the paper:
Are microorganisms in Browne Formation halite alive? Some halophilic microorganisms, such as Dunaliella algae, shrink and greatly reduce biological activity when host waters become too saline; these algal cells may be revived during later flooding events (Oren, 2005). Survival of bacteria and archaea in primary fluid inclusions in 97 and 150 ka halite have been described (Mormile et al., 2003; Lowenstein et al., 2011). The oldest known halite from which living prokaryotes have been extracted and cultured is Permian (ca. 250 Ma; Vreeland et al., 2000). Therefore, it is plausible that microorganisms from the Neoproterozoic Browne Formation are extant.
Possible survival of microorganisms over geologic time scales is not fully understood. It has been suggested that radiation would destroy organic matter over long time periods, yet Nicastro et al. (2002) found that buried 250 Ma halite was exposed to only negligible amounts of radiation. Additionally, microorganisms may survive in fluid inclusions by metabolic changes, including starvation survival and cyst stages, and coexistence with organic compounds or dead cells that could serve as nutrient sources (e.g., McGenity et al., 2000; Schubert et al., 2009a, 2010; Stan-Lotter and Fendrihan, 2015). One such organic compound, glycerol, produced by the cellular breakdown of some algae, may provide energy for longevity of coexisting prokaryotes (Schubert et al., 2010; Lowenstein et al., 2011). Furthermore, both non–spore-forming and spore-forming prokaryotes may have advantages for long-term survival in fluid inclusions. Non–spore-forming prokaryotes are continually, but minimally, metabolically active, so they are able to repair DNA should it be necessary (Johnson et al., 2007). Alternately, spores formed by prokaryotes may provide another way of longterm survival in a dormant state (Vreeland et al., 2000; Lowenstein et al., 2011).
Personally, I fully support an effort to revive these critters and study them. They’d be a fascinating look into the incredibly ancient past and at how life evolved. Of course, the best place for this research would be in the underground Wildfire facility a few miles west of Clavius Base.