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Title: The effect of rubratoxin B on the morphology and physiology of Aspergillus niger Van Tieghem
Author: Badii, Farah
ISNI:       0000 0001 3435 119X
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1980
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The rubratoxins are nonadrides produced by Penicillium rubrum which show some antifungal activity. Aspergillus niger and A. tamarii are particularly sensitive to this toxin. The presence of as little as 15 ug rubratoxin B/ml causes a reduction of growth of A. niger Van Tieghem as measured by the dry weight of mycelium produced. This concentration of toxin produces swelling, distortion and increased branching of the mycelium. The formation of swollen hyphal tips and distorted mycelium is not alleviated by increasing the osmotic pressure of the medium. When damaged mycelium grown in the presence of this toxin is transferred into a fresh medium without any toxin, it is able to develop normal mycelium and capable of producing normal spores. Despite the reduction of growth in the presence of a low concentration of toxin, glucose consumption is not affected as much as biomass production, and appears to be converted into metabolites such as pigments rather than biomass. Protoplasts of A. niger in the presence of this toxin are able to synthesize new cell wall and revert to mycelium, but the mycelium is abnormal, more branched, swollen and does not proceed to the formation of sporophores and conidiophores. Rubratoxin B,as well as reducing the growth rate, causes a depression of the oxygen uptake by A. niger as well as changes in the metabolic activity and chemical composition of the cell wall of this mould. This toxin causes a reduction in the protein content of the cell wall of A. niger and the liberation of a significant amount of protein, amino acids and pigments into the culture medium.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Botany