[Study of aeration and temperature effects on the biosynthesis of 5'-inosine acid by the Brevibacterium ammoniagenes mutant].

The biosynthesis of 5'-inosine acid (5'-IMP) by the culture Brevibacterium ammoniagenes 225--5 was studied under different aeration conditions. Intensive aeration (Kv = 3.6 g O2/l.hr) was found to be necessary for an active build-up of 5'-IMP. Reduced aeration (Kv = 3.6 g O2/l.hr) caused a decrease in the 5'-IMP yield, a simultaneous increase in the hypoxanthine concentration, a reduction of cell productivity and a decrease in the glucose transformation to 5'-IMP. The temperature of 28 degrees was shown to be optimal for the biosynthesis of 5'-IMP. The total build-up of purine derivatives (5'-IMP and hypoxanthine) decreased, if the first stage (the stage of hypoxanthine accumulation) or the entire fermentation took place at 37 degrees. The temperature rise from 28 to 37 degrees at the second stage of fermentation (the stage of 5'-IMP accumulation) resulted in a temporal increase in the 5'-IMP synthesis followed by its inhibition. The most intensive synthesis of 5'-IMP in the supernatant occurred at 37 degrees and pH 7.0-8.0. A short-term heating of the culture liquid (3 hrs at 37 degrees after 72 hrs fermentation) increased the yield of 5'-IMP during heating and, to the greatest extent, bu the end of fermentation.