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An ultrastructural examination of Penicillium urticae during the transition to antibiotic biosynthesis
Abstract:
The ultrastructure of Penicillium urticae mycelium was compared at various stages of submerged growth to examine changes associated with the onset of antibiotic biosynthesis. Penicillium urticae was shown to be a normal eukaryotic, septate, filamentous fungus with a variety of subcellular components. Younger mycelia possessed a denser cytoplasm which gave way to a more granular and vacuolated cytoplasm as the organism made the transition into antibiotic biosynthesis. An increase in the thickness, and perhaps the structural complexity, of the cell wall also occurred over the transition. There was evidence of a glycocalyx surrounding the hyphae. Discrete granules, termed peripheral particles, appeared and increased in number over the transition. Their biochemical content and possible involvement in patulin production was tested by examining P. urticae after growth in media of different composition, and by examining the ultrastructure of a patulin minus mutant, P3. The significance of these observations in relation to patulin production is discussed.
Insights
Changes in Penicillium urticae fungal cells during antibiotic production were observed. The cytoplasm and cell wall altered, and unique granules appeared, potentially aiding patulin biosynthesis.
Area of Science:
- Mycology
- Microbial Ultrastructure
- Antibiotic Biosynthesis
Background:
- Penicillium urticae is a filamentous fungus.
- Submerged growth stages are critical for antibiotic production.
- Understanding cellular changes is key to optimizing biosynthesis.
Purpose of the Study:
- To investigate the ultrastructural changes in Penicillium urticae during submerged growth.
- To correlate cellular morphology with the onset of antibiotic biosynthesis.
- To explore the role of specific cellular components in patulin production.
Main Methods:
- Comparative ultrastructural analysis of Penicillium urticae mycelia at different growth stages.
- Cultivation of P. urticae in varied media compositions.
- Ultrastructural examination of a patulin-deficient mutant (P3).
Main Results:
- Younger mycelia exhibited denser cytoplasm, transitioning to granular and vacuolated cytoplasm during antibiotic production.
- Increased cell wall thickness and complexity were observed.
- Peripheral particles appeared and increased in number during the transition to biosynthesis.
- Cellular changes were investigated in relation to patulin production, including studies on a mutant strain.
Conclusions:
- Significant ultrastructural alterations in Penicillium urticae correlate with the initiation of antibiotic biosynthesis.
- Peripheral particles may play a role in patulin production.
- Further research is needed to elucidate the precise function of these observed changes.