Microbiology of saturated salt solutions and other harsh environments. IV. New observations on ribonucleotide-induced recovery of KCl-habituated Penicillium notatum.

Salt-tolerant mutant Penicillium notatum sub-cultured in a glucose-peptone broth saturated with KCl shows continued attenuated growth when transferred to salt-free broth. Additional tests have shown E. coli S-RNA to be inferior to yeast RNA preparations, that base-free phosphate sources are inactive, but that nicotinamide adenine dinucleotide and flavine adenine dinucleotide are moderately active. All phosphate derivatives of adenine, cytosine and guanosine and inosine were active including 5'-polyphosphates, 3'(2')-monophosphates 5'-monophosphates, and adenine 3', 5'-cyclic monophosphate. Uracil derivatives were of low activity at best. Among base precursors, orotic acid was moderately active whereas imidazoles were not. The high activity of inosine 5'-phosphate a precursor of other purine nucleotides suggested that one mode of KCl action might involve a block in conversion of 4-amino-5-imidazole carboxamide ribonucleoside to the hypoxanthine nucleotide.