Carbon metabolism in model microbial systems from a temperate salt marsh

Area of Science:

• Marine Ecology
• Microbial Ecology
• Biogeochemistry

Background:

• Spartina alterniflora is a key salt marsh plant.
• Understanding its decomposition is vital for coastal ecosystem health.
• Microbial communities drive nutrient cycling in these environments.

Purpose of the Study:

• To investigate the microbial metabolism of Spartina alterniflora leachate.
• To compare the roles of bacteria, fungi, and mixed communities in decomposition.
• To identify factors influencing carbon mineralization and biomass production.

Main Methods:

• Laboratory experiments using 14C-labeled Spartina alterniflora leachate.
• Utilized mixed, bacterial-only, and fungal-only salt marsh microbial communities.
• Employed antibiotics to selectively inhibit microbial groups.
• Measured label uptake, mineralization, and particulate biomass production.

Main Results:

• Bacterial and mixed communities showed more rapid label uptake and extensive mineralization compared to fungi alone.
• Fungal communities were more efficient at converting leachate into particulate biomass (efficiency 0.82).
• Mixed communities had lower biomass production efficiency (0.21) but higher mineralization due to protozoa and microcrustaceans.
• Seawater-soluble plant fractions were most rapidly degraded.

Conclusions:

• Bacteria play a significant role in Spartina alterniflora leachate decomposition and mineralization.
• Fungi contribute substantially to biomass production from Spartina leachate.
• Mixed microbial communities, including microfauna, optimize both mineralization and biomass conversion in salt marsh ecosystems.