Abstract
Chemolithoheterotrophy describes a type of microbial metabolism by which organisms oxidise an inorganic electron donor to supplement the generation of an electrochemical gradient. This results in higher overall growth yields and maximum specific growth rates as the organism does not need to generate as many reducing equivalents to fuel the respiratory chain and can instead redirect that material into anabolic reactions to generate more biomass. Many aspects of this metabolism remain poorly understood due to the difficulty in observing genuine chemolithoheterotrophy, with significant increases in the maximum specific growth yield (YMAX) and maximum specific growth rate (µMAX) seen in continuous culture settings. This type of microbial metabolism offers several industrial benefits by offering a way to increase growth parameters most important to industrial microbiology, those being yield and growth rate. The presented work investigates several aspects of chemolithoheterotrophy in organisms previously used to examine this type of metabolism, namely Pseudomonas trautweinii and Achromobacteraegrifaciens culture B. Macromolecular fractions from lyophilised Pseudomonas trautweiniibiomass grown organoheterotrophically and chemolithoheterotrophically across carbon, phosphate and oxygen limited chemostats were examined to determine which cellular fraction or what combination was responsible for the documented increase in growth yield. Respiratory chain inhibitors were also used to determine the route through which electrons oxidised from the auxiliary electron donor, in this case thiosulfate, enter the respiratory chain. The data presented adds to the evidence that the main pathway of thiosulfate supported oxidative phosphorylation is through the terminal cytochrome-c oxidase via oxidation by thiosulfate dehydrogenase while also identifying the main macromolecular fraction which constitutes the observed increase in biomass.
Awarding Institution(s)
University of Plymouth
Supervisor
Anne Plessis, Rich Boden
Document Type
Thesis
Publication Date
2025
Embargo Period
2025-11-11
Deposit Date
November 2025
Additional Links
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Recommended Citation
Yarnley, C. (2025) Metabolic and Kinetic impacts of the auxiliary energy source in model chemolithoheterotrophic Bacteria. Thesis. University of Plymouth. Available at: https://doi.org/10.24382/rnk9-th86
