Early steps in microbial colonization processes at deep-sea hydrothermal vents

Area of Science:

• Deep-sea microbiology
• Hydrothermal vent ecosystems
• Microbial ecology

Background:

• Deep-sea hydrothermal vents host unique ecosystems, including symbiotic relationships between microorganisms and invertebrates like Alvinella spp. worms.
• Understanding the initial microbial colonization processes is crucial for deciphering the assembly and function of these specialized communities.

Purpose of the Study:

• To investigate the early-stage microbial colonization of Alvinella spp. habitats in situ.
• To identify the microbial communities that precede and accompany Alvinella spp. settlement on colonization devices.

Main Methods:

• Deployment of four colonization devices onto Alvinella spp. colonies at the East-Pacific Rise (EPR 13°N) for short (<1 week) and long (3 weeks) periods.
• In situ video imagery and monitoring of thermal and physico-chemical conditions.
• Analysis of microbial communities using molecular techniques and isolation of dominant bacterial groups.

Main Results:

• Microorganisms with specialized adhesion structures and extracellular matrices were observed, suggesting adaptations for surface colonization.
• Microbial mats were primarily composed of e-Proteobacteria; Archaea were notably absent.
• A dominant e-Proteobacteria phylotype (AlviH2) was identified across multiple colonization devices.
• Bacteria affiliated with Cytophaga-Flavobacterium-Bacteroides and e-Proteobacteria, capable of diverse metabolic strategies, were isolated.

Conclusions:

• Early colonization of Alvinella spp. habitats is dominated by e-Proteobacteria, potentially due to their physiological versatility and adaptability.
• The observed microbial consortia provide insights into the initial stages of community development in deep-sea vent environments.
• Specific microbial groups may play key roles in facilitating the settlement and habitat formation for Alvinella spp. worms.