Patterns of amino acid utilization by aquatic hyphomycetes

Area of Science:

• Aquatic mycology
• Biogeochemistry
• Ecology

Background:

• Leaf decomposition in streams is a key process in nutrient cycling.
• Aquatic hyphomycetes are primary decomposers of leaf litter in freshwater ecosystems.
• Amino acids are crucial nitrogen sources for fungal growth.

Purpose of the Study:

• To investigate the utilization of leaf-derived amino acids by aquatic hyphomycetes.
• To compare amino acid availability and fungal colonization on different leaf types (alder vs. beech).
• To model the transfer and uptake kinetics of amino acids.

Main Methods:

• Combined field and laboratory experiments involving leaf litter decomposition.
• Seasonal sampling of stream water and leaf material.
• Analysis of amino acid concentration in leaves and water.
• Fungal species identification and quantification.
• Mathematical modeling using differential equations.

Main Results:

• Leaf-drift environments had significantly higher amino acid concentrations than surface water.
• Protein amino acid content decreased exponentially, faster in alder than beech leaves.
• Aquatic hyphomycetes consumed 55-75% of leaf amino acids, showing robust growth, especially on alder.
• Alder leaves supported four times more fungal species than beech leaves.
• Fungal absorption of dissolved amino acids exhibited a switch-like behavior based on availability.

Conclusions:

• Aquatic hyphomycetes are efficient scavengers of leaf-derived amino acids, with nitrogen availability influencing leaf preference.
• Alder leaves provide a more favorable substrate for fungal colonization and growth due to higher initial amino acid content and diversity.
• Fungal nutrient uptake strategies are dynamic and responsive to environmental conditions.