Document Type
Dissertation
Degree
Doctor of Philosophy
Major
Biology
Date of Defense
5-8-2026
Graduate Advisor
Dr. Lon M. Chubiz
Committee
Dr. Xuemin Wang
Dr. Bethany K. Zolman
Dr. Alexander S. Bradley
Dr. Robert F. Inglis
Abstract
Acidobacteriota remain among the most cryptic groups of microbes despite widespread speculation regarding their functional roles in soils. Though largely uncharacterized, these have been associated with forming membrane spanning lipids (MSLs), iso-diabolic acid tetraester (iso-DT) and branched glycerol dialkyl glycerol tetraethers (brGDGT). MSLs hold significant importance in developing paleo-environmental scales. Canonically, formation of MSLs is an Archaeal feature presumably providing tolerance to extremophilic environment. Yet, their presence in Acidobacteriota raises important questions about their biosynthesis and physiology. It has been reported that MSLs are associated with phosphatidylhexose (PH) headgroup. The second chapter comprehensively investigated this association by using a direct infusion neutral loss-based method. I surveyed the lipidome of Acidobacteriota species across multiple culturable phylogenetic orders. I observed that MSLs were associated with PH headgroup whereby Acidobacteriota that lacked PH lipids also lacked MSLs. My research provided evidence that the biosynthesis of MSLs in Acidobacteriota occurs in a PH headgroup specific manner, an unusual membrane lipid biosynthesis feature. PH-MSLs have a unique mass spectrometry signature. The third chapter leverages this property to develop a high-throughput screening method using MSLs as a biomarker to isolate Acidobacteriota. I successfully isolated two unique Edaphobacter species from soil, thereby providing an alternative strategy to increase culturable Acidobacteriota species. While the two novel Edaphobacter species were isolated from the same soil sample, their genome architectures were heterogeneous. In the fourth chapter, I comprehensively explored this observation across the Edaphobacter genus. My analysis revealed that the genus represents a highly divergent genome architecture with an open pangenome (~19000 gene clusters) comprising a relatively small core genome (~1500 genes) unlike model bacterial organisms. Though the major focus was on Acidobacteriota, the fifth chapter explores microbial community assembly dynamics in a highly antagonistic intraspecific setting. By using 8 Pseudomonas aeruginosa strains, I investigated assembly outcomes at all levels of hierarchies, pairwise to 8-way combinations. I observed that an increase in complexity rather than pairwise interactions defined the outcomes of higher order communities. Bioinformatics analysis suggested that the outcomes were potentially mediated by phages, thus providing a unique aspect of the biotic factors affecting community assembly dynamics.
Recommended Citation
Gul, Danish, "Exploring the Complex Membrane Biology and Genetic Diversity of the Acidobacteriota via an Omics Approach" (2026). Dissertations. 1609.
https://irl.umsl.edu/dissertation/1609
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