Physiological and biochemical changes induced by osmolality in halotolerant aspergilli

Area of Science:

• Microbiology
• Environmental Science
• Biochemistry

Background:

• Hypersaline and alkaline environments pose significant challenges for microbial life.
• Understanding fungal adaptation to extreme conditions is crucial for ecological and biotechnological applications.
• Aspergillus species are known for their adaptability, but their resilience in specific extreme environments requires further investigation.

Purpose of the Study:

• To isolate and characterize halotolerant and alkali-resistant Aspergillus fungi from hypersaline soil.
• To investigate the effects of high salt concentrations on fungal growth, sporogenesis, and enzyme activity.
• To evaluate the potential of exogenous compatible solutes in enhancing fungal salt stress resistance.

Main Methods:

• Isolation of fungi using a complex medium with 20% NaCl.
• Determination of salt tolerance (up to 25% NaCl) and alkali resistance (up to pH 10.5).
• Assessment of compatible solute (trehalose, alpha-ketoglutarate, glycerol) effects on salt tolerance.
• Biochemical analyses including protein, carbohydrate, lipid content, PAGE, and TLC of amino acids.

Main Results:

• Aspergillus ventii and Aspergillus parasiticus were successfully isolated, demonstrating tolerance to 20-25% NaCl and pH 10.5.
• High salt concentrations negatively impacted sporogenesis and inhibited extracellular enzymes like lipases and amylases.
• Application of trehalose, alpha-ketoglutarate, and glycerol increased salt tolerance to 27.5-29% NaCl.

Conclusions:

• Aspergillus ventii and Aspergillus parasiticus possess robust mechanisms for adapting to hypersaline and alkaline conditions.
• Exogenous compatible solutes are effective in improving fungal osmotolerance.
• Biochemical analyses suggest species-specific adaptation strategies within the Aspergillus genus.