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- Title
Overproduction of NAD<sup>+</sup> and 5'-inosine monophosphate in the presence of 10 µM Mn<sup>2+</sup> by a mutant ofCorynebacterium ammoniageneswith thermosensitive nucleotide reduction (nrd<sup>ts</sup>) after temperature shift.
- Authors
Abbouni, Bouziane; Elhariry, Hesham M.; Auling, Georg
- Abstract
Corynebacterium ammoniagenesstrain CH31 is thermosensitive due to a mutation in nucleotide reduction (nrdts). The strain was examined for nucleotide overproduction upon shifting the culture temperature to a range of elevated temperatures. No overproduction of NAD+ was detected in the control maintained at 27°C whereas NAD+ was accumulated extracellularily by strain CH31 at 37°C and at 40°C. As a result of the temperature shift, division-inhibited cells displayed only limited elongation. This is a characteristic morphological feature of cell-cycle-arrested coryneform bacteria. Ribonucleotide reductase (RNR) activity was inactivated immediately after the temperature shift in the NAD+-proficient cultures, leading presumably to an exhaustion of deoxyribonucleotide pools and impairment of DNA replication. In contrast to the low extracellular accumulation of NAD+, at the non-permissive temperature of 35°C a distinct capacity for intracellular nucleotide overproduction was revealed by a new method using nucleotide-permeable cells. The approach of shifting the culture temperature was applied successfully to the overproduction of taste-enhancing nucleotides in the presence of 10 µM Mn2+. Concomitant with a dramatic loss of viability, the thermosensitive mutant CH31 accumulated 5.3 g 5'-inosine monophosphate per liter following the addition of hypoxanthine as precursor for the salvage pathway.
- Publication
Archives of Microbiology, 2004, Vol 182, Issue 2/3, p119
- ISSN
0302-8933
- Publication type
Academic Journal
- DOI
10.1007/s00203-004-0674-4