Closed microbial communities self-organize to persistently cycle carbon

Area of Science:

• Ecology
• Microbial Ecology
• Ecosystem Dynamics

Background:

• Nutrient and carbon cycling are fundamental emergent properties of ecosystems, crucial for their structure and persistence.
• Understanding how ecosystems sustain robust cycles is a central ecological problem, yet quantitatively studying this is difficult due to experimental challenges.
• Closed microbial ecosystems (CES) offer a tractable model for investigating ecosystem organization and function under controlled conditions.

Purpose of the Study:

• To develop a quantitative method for measuring carbon cycling in closed microbial ecosystems (CES).
• To investigate the self-organization and persistence of carbon cycling in CES composed of algae and diverse bacterial consortia.
• To determine the relationship between taxonomic composition and metabolic function in self-organizing microbial ecosystems.

Main Methods:

• Development of a novel technique for quantifying carbon cycling within hermetically sealed microbial communities.
• Establishment and long-term monitoring of closed microbial ecosystems (CES) comprising an alga and varied bacterial consortia.
• Comparative analysis of carbon cycling rates and taxonomic/metabolic profiles across replicate CES.

Main Results:

• CES composed of algae and diverse bacteria demonstrated robust carbon cycling for extended periods (months).
• Carbon cycling efficiency in CES was found to be largely independent of the specific bacterial taxa present.
• Despite significant taxonomic variation, self-organized CES consistently exhibited a conserved set of metabolic capabilities.

Conclusions:

• An emergent carbon cycle imposes metabolic constraints but not strict taxonomic constraints on ecosystem organization.
• Closed microbial ecosystems provide a powerful experimental framework for studying emergent ecosystem functions like nutrient cycling and persistence.
• This research establishes CES as valuable model systems for controlled ecological studies, enabling investigation of replicate systems with defined community composition and environmental parameters.