title: Influence of calcium on fungal growth, hyphal morphology and citric acid production in Aspergillus niger.
abstract: Addition of 0.5 g/L CaCl2 to the fermentation medium lowered the final biomass dry mass by 35% and increased the uptake of phosphate and sucrose, and the production of citric acid by 15, 35 and 50%, respectively. In a medium deprived of Ca2+ the microorganism displayed both a pelleted and a filamentous form of growth, the hyphae being scarcely branched, without bulbous cells. An addition of Ca2+ induced a pelleted form of growth, highly branched hyphae and numerous bulbous cells. Bulbous cells growing in the presence of Ca2+ exhibited cell walls composed of laminated layers, and featured vesicles associated with the wall and/or the cell membrane, containing numerous inclusions. The cytotoxic effect of high concentrations of citric acid in the medium as well as an increase of the activity of N-acetyl-beta-D-glucosaminidase, a lytic enzyme, might be involved in these morphological changes.
authors.affiliation: Planta Piloto de Procesos Industriales Microbiológicos, Tucumán, Argentina.
authors.forename: L M
authors.initials: LM
authors.lastname: Pera
authors.forename: D A
authors.initials: DA
authors.lastname: Callieri
mesh_terms: D001234:Aspergillus niger / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D002122:Calcium Chloride / Q000494:pharmacology*; D002462:Cell Membrane / Q000648:ultrastructure; D002473:Cell Wall / Q000648:ultrastructure; D019343:Citric Acid / Q000378:metabolism* / Q000633:toxicity; D008854:Microscopy, Electron; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism
chemical_list: D010758:Phosphorus; D019343:Citric Acid; D002122:Calcium Chloride; D009584:Nitrogen