Reversion by calcium of a yeast-like development to the original filamentous form, of the 10V10 5-fluorocytosine-sensitive mutant of Aspergillus niger

Abstract

Some filamentous fungi present the phenomenon of dimorphism, their morphological structure alterations being capable of inducing metabolism changes. The Aspergillus niger strain 10v10, a producer of citric acid, was submitted to the mutagenic action of ultraviolet irradiation which respectively selects mutants sensitive or resistant to the antifungi agent 5 fluorocytosine (5-FC). 5-FC sensitive mutants presented a morphological alteration to a yeast-like form. The effects of pH changes, addition of salts (KH 2 PO 4 , NH 4 NO 3 , MgSO4 and MgCl2), the presence of osmotic stabilizers, as well as of calcium chloride, on morphological reversal and acid production were studied. Morphological reversal to the filamentous form was observed only in the presence of CaCl 2 (500mM) for the mutants strains 1 and 2, while the acid production occurred in both, yeast-like and filamentous forms.

Effect of Extracellular Factors on Growth and Dimorphism of Rhizopus oryzae with Multiple Enzyme Synthesizing Ability

“…This might be due to the restoration of proper cell volume and maintenance of resting membrane potential by activated chloride channels, which was generally activated by Ca 2? [34], a report similar to the filament formation of Zymomonas mobilis [35] but contrary to that from R. oryzae [3], Aspergillus niger [1], P. marneffei [9]. Addition of Griseofulvin (mitotic inhibitor) and Flucanozole (cytochrome P450 1,4-a-demethylase inhibitor) caused appearance of intermediate and filamentous form respectively at 28°C but yeast like form at 37°C when the pseudohyphae got detached from the mycelium releasing a large number of yeast like cells (Fig.…”

“…Many filamentous fungi present the phenomenon of dimorphism [1], where a monokaryotic yeast form alternates with a dikaryotic hyphal form [2]. Interest in this phenomenon derives from the prevalence of dimorphism among the pathogenic fungi [3].…”