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[Resistance of mesospheric microorganisms to periodic freezing--thawing]
Abstract:
The object of this work was to study cytological changes caused by periodic freezing-thawing in the conidia of the fungi Aspergillus niger and Penicillium chrysogenum isolated from the mesosphere as well as in the conidia of the same species taken from the collection of microorganisms. The conidia from the mesosphere were found to be highly resistant to the treatment. As was shown by electron microscopy, the outer "backbone" layer of the spore envelope broke down and the membranes of the plasmalemma stratified after ten cycles in A. niger and P. chrysogenum. The percentage of conidia with the damaged ultrastructural organization was higher in mutants of these cultures.
Insights
Fungal conidia from the mesosphere showed high resistance to freezing-thawing. Electron microscopy revealed damage to spore envelopes and membranes in Aspergillus niger and Penicillium chrysogenum after ten cycles.
Area of Science:
- Mycology
- Extremophile Biology
- Cell Biology
Background:
- Fungal spores (conidia) exhibit remarkable resilience.
- Understanding conidial resistance is crucial for astrobiology and cryopreservation.
- Microorganisms from extreme environments like the mesosphere offer unique insights into survival mechanisms.
Purpose of the Study:
- To investigate the cytological effects of repeated freezing-thawing cycles on fungal conidia.
- To compare the resistance of mesospheric fungi with laboratory-cultured strains.
- To identify ultrastructural changes induced by cryopreservation stress.
Main Methods:
- Isolation of Aspergillus niger and Penicillium chrysogenum conidia from mesospheric samples and microbial collections.
- Application of periodic freezing-thawing cycles.
- Analysis of ultrastructural changes using transmission electron microscopy.
Main Results:
- Mesospheric fungal conidia demonstrated significant resistance to freezing-thawing.
- Ten cycles caused breakdown of the outer spore envelope layer and plasmalemma stratification in both species.
- Mutant strains exhibited a higher percentage of conidia with damaged ultrastructural organization.
Conclusions:
- Fungal conidia from the mesosphere possess enhanced cryotolerance.
- Periodic freezing-thawing induces specific ultrastructural damage in conidia.
- Mutant fungal strains may be more susceptible to cryopreservation-induced stress.