Studies on 5′-Nucleotidase-Lacking Mutants Derived from Bacillus subtilis

Two 5′-nucleotidase-lacking mutants, R–42 and A–1, were derived from an adenine-requiring mutant, B. subtilis 1145–2–83, which has productivity of both inosine and hypoxanthine. Strain A–1 accumulated 5′-IMP as well as inosine and hypoxanthine, and strain R–42 accumulated 5′-IMP and 5′-GMP as well as inosine and hypoxanthine in their culture fluids. These mutants responded to either adenine or adenosine, but did not to 5′-AMP. This fact suggests that adenine or adenosine may be incorporated into the cells, but 5′-AMP may neither be incorporated into the cells nor be degraded during culture. 5′-GMP was converted to 5′-IMP, and 5′-AMP was phosphrylated to ADP in the growing culture of strain A–1.