• Journal of Microbiology and Biotechnology
• /
• v.16 no.7
• /
• pp.999-1009
• /
• 2006

Physiological, biochemical and genetic studies of Corynebacterium glutamicum, a workhorse of white biotechnology used for amino acid production, led to a waste knowledge mainly about amino acid biosynthetic pathways and the central carbon metabolism of this bacterium. Spurred by the availability of the genome sequence and of genome-based experimental methods such as DNA microarray analysis, research on genetic regulation came into focus. Recent progress on mechanisms of genetic regulation of the carbon, nitrogen, sulfur and phosphorus metabolism in C. glutamicum will be discussed.

• Journal of Nutrition and Health
• /
• v.21 no.1
• /
• pp.47-60
• /
• 1988

This study was performed to investigate the effect of dietary levels on protein metabolism in eight healthy Korean adult females. The 20-day metabolic study consisted of 2 day adaptation period and three 6-day experimental. Three experimental diets were low protein (LP : protein 44g), high protein(HP : protein 85g) and high animal protein (HAP : protein-84g). The apparent absorption and balance on nitrogen were significantly higher in high protein than in low protein diet. Nitrogen, absorption rate was about 75% for low protein and about 85% for high protein intake. The mean values of nitrogen balance were -1.28% for low protein and 0.78% for high protein diet. All the subjects were in negative nitrogen balance at the low protein intake while they were in positive nitrogen balance at the high protein intake. The mean daily urinary nitrogen excretion increased with increased level of protein intake. Urea nitrogen was the largest part of the urinary nitrogen. The ratio of urea nitrogen to total urinary nitrogen increased significantly for 79 to 85% as protein intake was doubled.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.2
• /
• pp.187-194
• /
• 2007

In order to utilize different nitrogen sources and to survive in a situation of nitrogen limitation, microorganisms have developed sophisticated mechanisms to adapt their metabolism to a changing nitrogen supply. In this communication, the recent knowledge of nitrogen regulation in the amino acid producer Corynebacterium glutamicum is summarized. The core adaptations of C. glutamicum to nitrogen limitation on the level of transcription are controlled by the global regulator AmtR. Further components of the signal pathway are GlnK, a $P_{II}-type$ signal transduction protein, and GlnD. Mechanisms involved in nitrogen control in C. glutamicum regulating gene expression and protein activity are repression of transcription, protein-complex formation, protein modification by adenylylation, change of intracellular localization, and proteolysis.

• Proceedings of the Korean Society of Plant Biotechnology Conference
• /
• 2005.11a
• /
• pp.65-70
• /
• 2005

A growing body of evidence shows that nitric oxide $({\cdot}NO)$ and ${\cdot}NO-derived$ reactive nitrogen species (RNS) act as both plant physiological regulators and stressors. However, very little is known concerning metabolism of RNS in plant cells. In this paper, we explore a plant metabolic basis for RNS, with special emphasis on the possible relationship to nitrogen assimilation, and discuss the potential of the metabolic engineering for plant-biotechnological application.

• BMB Reports
• /
• v.35 no.5
• /
• pp.443-451
• /
• 2002

Malonate is a three-carbon dicarboxylic acid. It is well known as a competitive inhibitor of succinate dehydrogenase. It occurs naturally in biological systems, such as legumes and developing rat brains, which indicates that it may play an important role in symbiotic nitrogen metabolism and brain development. Recently, enzymes that are related to malonate metabolism were discovered and characterized. The genes that encode the enzymes were isolated, and the regulation of their expression was also studied. The mutant bacteria, in which the malonate-metabolizing gene was deleted, lost its primary function, symbiosis, between Rhizobium leguminosarium bv trifolii and clover. This suggests that malonate metabolism is essential in symbiotic nitrogen metabolism, at least in clover nodules. In addition to these, the genes matB and matC have been successfully used for generation of the industrial strain of Streptomyces for the production of antibiotics.

• Journal of Plant Biology
• /
• v.7 no.1
• /
• pp.11-14
• /
• 1964

Change of the amount of carbohydrates in relations with nitrogen metabolism was studied under the different manners of supply and with different sources of nitrogen. In barley plant supplied with nitrogen through root, the depression periods of glucose and sucrose content occurred at 2 days after, but the amounts of both sugars were different with the different sources of nitrogen; there were in sequence diminished by treatment of NO3, NH4 and urea. In sunflower leaves sprayed with urea both sugar contents were inversely related to the urea concentration sprayed, and depressing periods of the sugars appeared immediately in the N-deficient plant but late in the N-abundant one.

• Journal of Plant Biology
• /
• v.4 no.2
• /
• pp.51-61
• /
• 1961

In order to detect the way of absorption and metaboism of the urea it is sprayed on the surface of the leaves of sunflower. The sunflowers used in this study are grown in different conditions such that the one in nittogen aboundant and the other in nitrogen deficient soil, respectively. The urea-N, ammonia-N, amide-N, and 80% alcohol soluble-N in the leaves were quantitatively determined. All of the nitrogenous components measured are generally tended to increased with rising the concentration of urea except only amide-N at 24 hours after sprayed, and these were highly significances. It seemed that hydrolizing of urea into ammonia and carbon dixide and the assimilation of ammonia into other organic nitrogenous constituents were rapid in the young leaves than in the mature. It is interest that the amide content, in the young leaves and nitrogen defieient one were enhanced with the increasing concentration of urea, although in the mature leaves it did not show any change in the urea treatment. It is presumed that the assimilation rate of ammonia and the urease activity were lower in the matture leaves than in the young and nitrogen deficient leaves. No significance at 5% level showed all of the nitrogenous components except total nitrogen between nitrogen abundant and deficent leaves. Urea content was a high peak at first 12 hours, ammonia at 48 hours, and amide and alcohol soluble nitrogen at 96 hours, whence decrease4d the content of these constituents gradually. The total nitrogen content is not incrased obviously by only one time of urea spray in this study. When the concentration of urea was relatively high there appeared the wilting spots on t도 edge of leaves. As a whole, it seemed that sprayed urea was rapidly absorbed and taken part in nitrogen metabolism within relatively short period.

• Journal of Microbiology and Biotechnology
• /
• v.2 no.4
• /
• pp.255-259
• /
• 1992

The effect of nitrate, nitrite and ammonia as inorganic nitrogen sources on the modulation of nitrogen metabolism of Botryococcus braunii UTEX.-572 has been studied under aeration. The primary process in the regulation of nitrogen metabolism by this alga has the nitrate uptake system. This uptake of nitrate operation was immediately inhibited by the presence of 0.5 mM of ammonium and reversed by 0.2∼0.3 mM ammonium. When cell were exposed to 5 mM of ammonium for 24 hours the activity of nitrate reductase became inactive.

• Journal of Nutrition and Health
• /
• v.6 no.3
• /
• pp.9-15
• /
• 1973

Some effect on the protein metabolism in growing albino rats by feeding on the rice mixed with wheat or barley have been studied. The species of wheat and barley used in this experiment were either 80% polished or nonpolished wheat, barley and naked barley. The growing rats to be examined were fed on 30% wheat or barley mixed with rice diets for 8 weeks. The total nitrogen, creatinine, amino acid nitrogen and urea-nitrogen contents in the liver and the creatinine and urea-nitrogen contents in the urine have been measured. The results obtained are summarized as follows: 1. The total nitrogen contents in the liver and the serum were no remarkable difference by feeding on each mixed diet, compared with the rice diet group. 2. The creatinine contents in the liver of the unpolished wheat and barley mixed diet groups were the similar to that of the rice diet group, but these were higher by feeding on the polished wheat and barley mixed with rice diets. 3. The amino acid nitrogen contents in the liver of the polished naked barley mixed with rice diet groups were the similar to that of the rice diet group, but these were higher by feeding on the other mixed diets than the rice diet. 4. The urea-nitrogen contents in the serum of the polished wheat and naked barley mixed with rice diet groups were higher than that of the rice diet group, but these were significantly lower by feeding on the polished barley mixed with rice diets than the others. 5. The creatinine and the urea-nitrogen contents in the urine of the original wheat and barley mixed with rice diet groups were higher than that of the polished wheat and barley mixed with rice diet groups. In the view of the above results, it could be seen that the protein metabolism was remarkable change according to polish of the wheat and barley.

• Korean Journal of Environmental Biology
• /
• v.27 no.3
• /
• pp.279-284
• /
• 2009

In order to understand food sources-metabolism for the pacific oyster (Crassostrea gigas), the stable isotope ratios of carbon (${\delta}^{13}C$) and nitrogen (${\delta}^{15}N$) of its gut, gill, and muscle as well as potential food sources (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass detritus) were determined in Dongdae Bay. Average ${\delta}^{13}C$ and ${\delta}^{15}N$ values reflect that oysters primarily fed on sedimentary organic matter as opposed to suspended organic matter during summer and winter seasons. However, the relatively enriched $^{15}N$ values of particulate organic matter (>$250{\mu}m$) and sedimentary organic matter in the summer may be due to the photosynthetic incorporation of $^{15}N$-enriched nitrogen (DIN) or the spawning events of bivalves. Specific oyster tissues (gut, gill, and muscle) revealed different metabolic pathways, which were determined through analysis of ${\delta}^{13}C$ and ${\delta}^{15}N$ in each organ. The present results suggest the determination of carbon and nitrogen stable isotopes to be a useful approach in ecological research related to the food sources- metabolism of Crassostrea gigas.