Changes In Nitrogen Source Research Articles

Effect of Nitrogen on Yield Using Bioenergetics Theory

The form of nitrogen influences the yield of microorganisms from a given amount of substrate. Previous work on calculating yields from thermodynamic principles is modified to give a correct account for the form of nitrogen. Nitrogen in the reduced form of ammonia contributes energy toward cell synthesis while the more highly oxidized forms of nitrogen require an expenditure of energy. In addition, the electron equivalency of cells changes depending on the form of nitrogen available to the microorganisms. These principles are incorporated into two approaches that yield equivalent results to formulate the overall reaction stoichiometry for substrate, nitrogen source, cells, and other products based on bioenergetics. An example is given where the change of nitrogen source from nitrate to ammonia results in an increase in cell yield of 29%.

Microbial oxidation of alpha-pinene by Serratia marcescens

A strain of the bacterium Serratia marcescens, isolated from sewage sludge, can oxidise the terpene hydrocarbon α-pinene to produce rans-verbenol as the major product, with verbeone and trans-sobrerol as minor products. A change in nitrogen source and inclusion of glucose as a second carbon source caused the bacterium to produce α-terpineol as the major oxidation product. Products were identified by gas liquid chromatography and mass spectrometry.

The regulation of the ammonia assimilatory enzymes in Rel+ and Rel- strains of Salmonella typhimurium.

The influence of the relA1 mutation on the regulation of the ammonia assimilatory enzymes, glutamate dehydrogenase (EC 1.4.1.4), glutamine synthetase (EC 6.3.1.2), and glutamate synthase (EC 1.4.1.3), was examined. When cells grown in rich media (either Luria broth or glucose-ammonia plus casamino acids) were transferred to a glucose-ammonia medium, the relA mutant failed to resume growth and did not have the same increase in any of the assimilatory enzyme activities as the rel+ strain. This effect was particularly dramatic for glutamate dehydrogenase, which increased 6-fold in the rel+ strain. Measurements of the guanosine nucleotide concentrations showed that the rel+ strain had a ppGpp concentration about 9 times that of the relA mutant 5 min after the shift to minimal medium. These results are consistent with those for other biosynthetic enzymes and show that the ammonia assimilatory enzymes require a relA product for their synthesis during shift from rich to minimal media. In addition, we examined the response of these strains to a change in nitrogen source. The relA mutant again failed to resume growth after a shift from glucose-ammonia to glucose-arginine medium. Even though the ppGpp concentration did not increase, the rel+ strain grew and increased glutamine synthetase activities about 2-fold. These changes the absence of increased ppGpp levels suggest that some other relA-mediated function is important during this change in nitrogen source.

Changes in the Enzyme Pattern in Synchronous Chlorella sorokiniana caused by Different Nitrogen Sources

Summary Changes in enzyme pattern in synchronous Chlorella sorokiniana (high temperature strain) due to changes in nitrogen source have been investigated. Regulation of nitrogen metabolism caused by change in the nitrogen source mainly effects the nitrate reducing system, glutamine synthetase, glutamate synthase and NADP-glutamate dehydrogenase. An intermediary effect has been shown on NAD-glutamate dehydrogenase and glutamate-oxalacetat-transaminase which were not directly involved in the regulating process.

Fumgal lipids. I. Effect of different nitrogen sources on the chemical composition.

AbstractThe effect of three nitrogen sources on the chemical composition of seven fungi, namely: Aspergillus niger, A. luchuensis, Penicillium crustosum, Alternaria tenuis, Rhizoctonia solani, Mucor sp. and Pythium irregulare has been studied. The various fungi showed a great variation with respect to lipid percentage and total lipid content. Lipid content varied from 3.2 to 41.5%. Non‐polar lipids were comprised of monoglycerides, diglycerides, free sterols, free fatty acids and triglycerides. The quantitative make‐up of the non‐polar lipid varied with different nitrogen sources. Palmitic, stearic, oleic and linoleic acids were the major fatty acids while lauric, myristic, palmitoleic, linoleic and arachidic were the minor ones. The fatty acid composition was dramatically changed by changing the nitrogen source. Since different fungi responded differently to changes in nitrogen source, no generalisation could be made.Two‐dimensional thin‐layer chromatography of the polar lipid fraction of these fungi revealed the presence of a maximum of fifteen spots. Phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl inositol were the major spots while lysophosphatidyl choline, lysophosphatidyl ethanolamine and phosphatidyl glycerol were present in smaller quantities. In comparison to phospholipids, glycolipids (except sterol glycoside) were present in relatively lower concentration. Pythium irregulare was very characteristic in having no glycolipids at all.