Abstract: | Clostridium cylindrosporum spores germinated rapidly under reducing conditions when bicarbonate, uric acid, and calcium were present. Germination rates on 10 mM urate increased with increasing Ca2+ (maximum rate at 5 mM Ca2+ or greater). Germination rates on urate (limiting Ca2+) increased with increasing urate concentrations to 10 mM urate. At 10 mM Ca2+, germination rates reached a maximum at 1 mM urate and remained constant thereafter. Cations (Na+, K+, Li+, and Mg2+), purines, purine analogs, and EDTA inhibited germination at limiting calcium concentrations but not (except for 10 mM adenine) at 10 mM Ca2+. Methyl viologen or formate did not inhibit germination. Germination was not observed in solutions containing xanthine, hypoxanthine, caffeine, theophylline, 6,8-dihydroxypurine, adenine, allopurinol, formate, glycine, or acetate, even though some of the purines are growth substrates. |