Mimicking biofilms: Photosynthetic assessments of C. reinhardtii in 3 physical forms

Author

John Michael Roesgen, University of New Mexico - Main CampusFollow

Publication Date

Fall 11-14-2023

Abstract

Oxygenic photosynthesis supports the majority of life on Earth through the capture of energy from sunlight and the assimilation of CO₂ into basic building blocks of cells. Microalgae are fast growing and account for about half of global photosynthesis. In addition, they can be cultivated and their metabolism can be redirected to generate additional useful products ranging from biofuels to pharmaceuticals. However, the efficiency of metabolite production is severely impacted by the slow diffusion of CO₂ through water and the high energetic costs of harvesting microalgae from liquid cultures. Microalgae grow in open water, but they also form biofilms that require less energy to harvest. However, the impact of these different growth forms on rates of photosynthesis is poorly understood. The work in this dissertation explores the importance of growth form on photosynthesis by examining CO₂ assimilation of the green microalga, Chlamydomonas reinhardtii, within three different states: as a liquid suspension, as a simple filtered two-dimensional artificial biofilm, and within a silica sol-gel encapsulation matrix as an example of a more complex biofilm. The rates of CO₂ assimilation were decreased within the simple filtered biofilm and further decreased within the silica sol-gel matrix. The decrease is thought to be due to the diffusional limitations to CO₂ imposed by the biofilm forms. Estimated rates of assimilation of CO₂ were also calculated from chlorophyll fluorescence values of both biofilms and were more similar to the measured liquid suspension rates, suggesting a persistent energetic imbalance between light and CO₂ capture in biofilms. This effort required development of new empirical corrections to correctly assess CO₂ exchange rates, and novel approaches to collect data that could be directly compared between the three forms.

Keywords

biofilm, gas-exchange, photosynthesis, silica sol-gel, carbon concentrating mechanism

Document Type

Dissertation

Degree Name

Biology

Level of Degree

Doctoral

Department Name

UNM Biology Department

First Committee Member (Chair)

David Hanson

Second Committee Member

Rebecca Bixby

Third Committee Member

Andrew Schuler

Fourth Committee Member

Taraka Dale

Recommended Citation

Roesgen, John Michael. "Mimicking biofilms: Photosynthetic assessments of C. reinhardtii in 3 physical forms." (2023). https://digitalrepository.unm.edu/biol_etds/519