Macrococcus sodonenszs KY 3765 and Arthrobacter cztreus KY 3155 were found capable of accumulating I M P in media supplemented with hypoxanthine as a precursor. High concentrations of phosphate and magnesium salts were required for high yields of I3zIP. Manganese deficiency in the media was also essential.
Excessive ?*ln2+ effects were also seen in the I M P fermentation carried out with an adenineless mutant of Cornynebacterzum glutamicum. In M . sodonenszs, R5P-like substances, 5-phosphoribose pyrophosphokinase and I M P pyrophosphorylase, were leaked out of the cells grown in suboptimal Mn*+ levels. This excretion was inhibited by high levels of h W + . Such a phenomenon was not noted in A . cztreus. An adenineless mutant (KY 7208) of Brevzbacterium ammonzagenes was found to accumulate an appreciable amount of IMP. The chemical changes in this fermentation shon ed that hypoxanthine was first produced de novo, excreted, and then reconverted into IlllP by a salvage pathway. When hypoxanthine was added to 7208 culture, I M P yield was increased appreciably. I n fact exogenous 14C-hypoxanthine was incorporated into 14C-IMP. Subsequent experiments showed that indeed B r . ammonzagenes ATCC 6872, a parent culture of KY 7208, was able to produce I l I P , GMP, and AMP, in good yield from hypoxanthine, guanine, and adenine, respectively.