Microbial Community Dynamics in Early Tufa Biofilms.

Area of Science:

• Geomicrobiology
• Freshwater Ecology
• Biogeochemistry

Background:

• Karst freshwater systems are unique ecosystems characterized by calcium carbonate precipitation and tufa barrier formation.
• Microbial communities play a critical role in initiating and stabilizing these tufa structures.

Purpose of the Study:

• To investigate the composition, diversity, and functional potential of prokaryotic and microeukaryotic communities during early-stage tufa formation.
• To examine temporal and spatial microbial dynamics in tufa biofilms at Plitvice Lakes National Park.

Main Methods:

• High-throughput sequencing of prokaryotic and microeukaryotic communities.
• Sampling of tufa and water over a 5-day period across two seasons at two distinct sites.
• Analysis of microbial community structure and inferred functional roles in tufa precipitation.

Main Results:

• Prokaryotic communities in early tufa biofilms stabilized quickly, dominated by genera like Bacillus and Delftia, involved in carbonate precipitation.
• Biofilm maturation led to shifts towards Acinetobacter and Rhodoferax, indicating increased heterotrophic activity.
• Microeukaryotic communities, including diatoms, contributed to extracellular polymeric substance production, aiding carbonate entrapment.

Conclusions:

• Microbial succession and community specialization are vital for the formation and stability of tufa barriers in karst freshwater systems.
• Findings provide insights into the microbial contribution to biogeochemical processes in these unique environments.