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Arch Microbiol. 2004 Oct;182(2-3):119-25. Epub 2004 Aug 31.

Overproduction of NAD+ and 5'-inosine monophosphate in the presence of 10 microM Mn2+ by a mutant of Corynebacterium ammoniagenes with thermosensitive nucleotide reduction (nrd(ts)) after temperature shift.

Author information

1
Institut für Mikrobiologie, Universität Hannover, Schneiderberg 50, 30167 Hannover, Germany.

Abstract

Corynebacterium ammoniagenes strain CH31 is thermosensitive due to a mutation in nucleotide reduction ( nrd(ts)). 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 degrees C whereas NAD(+) was accumulated extracellularily by strain CH31 at 37 degrees C and at 40 degrees 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 degrees 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 microM Mn(2+). 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.

PMID:
15340797
DOI:
10.1007/s00203-004-0674-4
[Indexed for MEDLINE]

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