• Korean Journal of Microbiology
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• v.26 no.2
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• pp.93-100
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• 1988

In order to understand the regulation of glutamate dehydrogenase(GDH) synthesis in Brevibacterium flavum, we have isolated a mutant lacking NADP-linked GDH activity by ethlmethane sulfonate treatment. The $gdh^-$ mutant was grown on the minimal plate with 1mM ammonium chloride and not that with 300mM ammonium chloride. The cell-free extracts from $gdh^-$ mutant and prototroph were also examined with glutamine synthetase(GS) and glutamate synthase (GOGAT) production by niteogen sources. The growth of $gdh^-$ mutant in presence of 20mM ammonium chloride means that GOGAT synthesis is sufficient to allow growth in this condition. GS production of $gdh^-$ mutant as well as parental strain was induced by 1mM urea and ammonium tartrate, but it was repressed by higher concentration of ammonia, and also induced by 20mM to 50mM glutamate as a substrate. It was special attention that GOGAT synthesis from $gdh^-$ strain was more repressed by higher concentration of ammonia than prototroph as described in E. coli system.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.304-309
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• 1989

The effects of simazine [2-chloro-4, 6-bis(methylamino)-s-triazine] on in vivo nitrogenase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase which are important in nitrogen assimilation of Rhodopseudomonas sphaeroides were investigated. Simazine inhibited the synthesis of nitrogenase and glutamine synthetase. The activity of glutamine synthetase in crude extracts of Rhodopseudomonas sphaeroides is less inhibited by simazine than that of glutamate synthase and glutamate dehydrogenase. These results suggest the possibility that simazine inhibits photosynthetic activity and so inhibits the synthesis of nitrogenase and glutamine synthetase in Rhodopseudomonas sphaeroides.