title: Effect of trace elements on citric acid fermentation by Aspergillus niger.
abstract: Citric acid yields of 98.7% (sugar consumption basis) were reached in shaker flasks with mutant UV-ET-71-15 of Aspergillus niger in a resin-treated sucrose medium of the following composition (g/100 ml): sucrose, 14.0; NH(4)NO(3), 0.20; KH(2)PO(4), 0.10; MgSO(4).7H(2)O, 0.025; and (mg/liter): FeSO(4), 0.15 to 0.75; ZnSO(4), 0.10; and CuSO(4), 0.01. Yields of 75% were obtained in medium with resin-treated clarified syrup and 68% with ferrocyanide-treated blackstrap molasses. Optimal conditions included selection of appropriate pellets as inoculum at 3%, pH of 4.5, temperature at 30 C, agitation at 250 rev/min, and fermentation time of 8 days. The mutant tolerated high concentrations of trace elements.
mesh_terms: D001230:Aspergillus / Q000187:drug effects / Q000378:metabolism*; D001389:Azirines; D002849:Chromatography, Gas; D002951:Citrates / Q000096:biosynthesis*; D003300:Copper / Q000494:pharmacology; D003470:Culture Media; D005285:Fermentation / Q000187:drug effects*; D005295:Ferrocyanides / Q000494:pharmacology; D005827:Genetics, Microbial; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008965:Molasses; D009153:Mutagens; D009154:Mutation; D012116:Resins, Plant / Q000494:pharmacology; D013053:Spectrophotometry; D013395:Sucrose; D014131:Trace Elements / Q000494:pharmacology*; D014466:Ultraviolet Rays; D015032:Zinc / Q000494:pharmacology
chemical_list: D001389:Azirines; D002951:Citrates; D003470:Culture Media; D005295:Ferrocyanides; D009153:Mutagens; D012116:Resins, Plant; D014131:Trace Elements; D008345:Manganese; D013395:Sucrose; D003300:Copper; D007501:Iron; D015032:Zinc