title: Optimization of nitrogen for enhanced citric acid productivity by a 2-deoxy D-glucose resistant culture of Aspergillus niger NGd-280.
abstract: The present investigation is concerned with the optimization of nitrogen for enhanced citric acid productivity by a 2-deoxy D-glucose resistant culture of Aspergillus niger NGd-280 in a 15 l stirred tank bioreactor. Nutrients, especially nitrogen source have a marked influence on citrate productivity because it is an essential constituent of basal cell proteins. Citric acid has been known to be produced when the nitrogen source was the limiting factor. Ammonium nitrate was employed as a nitrogen source in the present study and batch culture experiments were carried out under various concentrations of ammonium nitrate. Specific growth rate was decreased and the biosynthesis of citric acid was delayed at higher concentrations of ammonium nitrate. Specific citric acid production rate was the highest when intracellular ammonium ion concentration was between 2.0 and 3.0 mmol g(-1) cells. Citrate production was however, stopped when intracellular ammonium ion concentration decreased below 1.0 mmol g(-1) cell.
authors.affiliation: Department of Botany, Biotechnology Research Laboratories, G.C University, Lahore, Pakistan.
authors.lastname: Ikram-Ul-Haq
authors.forename: Sikander
authors.initials: S
authors.lastname: Ali
authors.forename: M A
authors.initials: MA
authors.lastname: Qadeer
authors.forename: Javed
authors.initials: J
authors.lastname: Iqbal
mesh_terms: D001234:Aspergillus niger / Q000254:growth & development / Q000378:metabolism*; D019149:Bioreactors; D019343:Citric Acid / Q000302:isolation & purification* / Q000378:metabolism; D003124:Colorimetry; D005285:Fermentation; D007700:Kinetics; D008965:Molasses; D009566:Nitrates; D009584:Nitrogen / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D009566:Nitrates; D019343:Citric Acid; D009584:Nitrogen; C006568:ammonium nitrate