Carbon cycling and functional redundancy in closed microbial ecosystems

Life on Earth depends on ecologically driven nutrient cycles to regenerate resources. Understanding how nutrient cycles emerge from a complex web of ecological processes is a central challenge in ecology. However, we lack model ecosystems that can be replicated, manipulated, and quantified in the laboratory, making it challenging to determine how changes in composition and the environment impact cycling. The goals of my work were to understand how carbon cycling arises in microbial communities and how community structure impacts the capacity to cycle carbon. Enabled by a new high-precision method to quantify carbon cycling, we show that materially closed microbial ecosystems (CES) provided with only light self-organized to robustly cycle carbon. Studying replicate CES that support carbon cycles revealed variable community composition but a conserved set of metabolic capabilities. We demonstrate that carbon cycling arises in functionally redundant communities in CES. We then focused on studying how community structure impacts the carbon cycling capacity of CES. To explore the functional landscape of carbon cycling CES within a reasonbale timeframe, we constructed a consumer-resource model of a CES. The model incorporates thermodynamics, autotroph and heterotroph consumers and necromass recycling. A library of CES were simulated and regression methods were employed to find a mapping between community composition and carbon cycling rates. Our model supports that functionally redundant communities are mainly composed of consumer generalists. Furthermore, we find that communities composed of generalists are more amenable to our regression approach than communities composed of specialists. We argue that this difference in predictive power might arise from disparities in the ruggedness of the functional landscapes of CES composed of generalist versus specialists. Our study helps establish CES as model biospheres for studying how ecosystems persistently cycle nutrients and provides one of the few concrete physical instances of functional redundancy in ecology.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• de Jesus-Astacio, Luis Miguel

Contributors dc:contributor

• Kuehn, Seppe
• O’Dwyer, James
• Metcalf, William W
• Cooper, Stephen L

• Microbial Ecology
• Closed Microbial Ecosystem
• Carbon Cycling
• Functional Redundancy
• Consumer-resource Model

Statement dc:rights

• © Luis Miguel de Jesús Astacio, Urbana, 2023

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/120259

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F120259