Life and the outer planets I. Performance of terrestrial organisms in ammonia-rich systems

Survival and growth of organisms has been demonstrated at 298 degrees K in NH3 atmospheres, including ammonia-methane mixtures. Included are bacteria such as Clostridium perfringens, Pseudomonas aeruginosa, fungi such as Penicillium notatum and Torula utilis. Although the biological response in onion and other species of Allium is limited to germination, standard metabolic poisons were active even in 15 M aqueous NH3, at 250 degrees K. The most extreme example of compatibility between NH3-rich environments and terrestrial life was the retention of metabolic capabilities by conidia of Penicillium after 6 months at 233 degrees K in a liquid ammonia-glycerol medium. Tritiated thymidine, uridine and amino acids were incorporated by these conidia unless subjected to intense gamma-radiation. Observations spanning the past decade suggest that the analogies between H2O and NH3 as solvent media or -OH and -NH2, as functional groups are probably valid. Chemical-biological evolution similar to early terrestrial evolution could be compatible with chemical conditions presumed to exist on the outer planets and some of their satellites.