Deep ocean prokaryotic communities are remarkably malleable when facing long-term starvation

Area of Science:

• Deep-sea microbial ecology
• Oceanography
• Microbiology

Background:

• The bathypelagic ocean is a vast ecosystem relying on surface particles for microbial activity.
• Surface-derived carbon may be insufficient for deep-sea prokaryotes' energy needs.
• Understanding microbial responses to carbon deprivation is crucial.

Purpose of the Study:

• To investigate the long-term dynamics of bathypelagic prokaryotes under carbon-limited conditions.
• To identify mechanisms enabling microbial survival and succession without external carbon input.

Main Methods:

• A 1-year experiment using an enclosed bathypelagic microbial community.
• Monitoring prokaryotic phylotype succession and community dynamics.
• Analyzing the role of specific taxa, like Thaumarchaeota, in carbon cycling.

Main Results:

• Continuous succession of active prokaryotic phylotypes occurred despite the lack of external energy.
• A rare Thaumarchaeota OTU dominated for 4 months, introducing organic carbon via chemolithoautotrophy.
• This introduced carbon created a priming effect, boosting community diversity and metabolic potential.

Conclusions:

• Bathypelagic microbial communities exhibit profound versatility in the face of organic carbon deprivation.
• Chemolithoautotrophic bacteria can sustain deep-sea ecosystems by introducing new carbon.
• Recruitment from a seed bank and niche specialization drive microbial succession in oligotrophic environments.