First Advisor

Kenneth Stedman

Date of Publication

Winter 3-1-2013

Document Type


Degree Name

Master of Science (M.S.) in Biology






Fungus-bacterium relationships, Endosymbiosis, Zygomycetes, Ascomycetes



Physical Description

1 online resource (viii, 92 pages)


Organisms belonging to the Kingdom Fungi are known to occupy a wide variety of ecological niches and are found globally in virtually all environments. Two members of the smallest of the fungal phylum, the Zygomycota, have also been found to harbor intercellular bacteria initially described as being from or closely related to organisms from the Genus Burkholderia. In this study two microaerophilic members of the species Verticilium from the phyla Ascomycota were characterized. Both appear to carry two bacterial endosymbionts. This is the first evidence of bacterial endosymbionts found within a member of the Ascomycota. Through the use of fluorescent stains, isolation of the intercellular bacteria, DNA analysis and fluorescent in situ hybridization (FISH) it appears that the newly isolated Verticilium sp. fungi contain not one but two bacterial endosymbionts from the family Proteobacteria. One putative symbiont is from the genus Bradyrhizobium, a member of the α-Proteobacteria, and one from the genus Burkholderia, a member of the β-Proteobacteria. This is the first evidence of a fungus containing not one, but two distinct endosymbionts from two separate bacterial families. Additionally the fungi were found to grow from spore across a large pH gradient (pH 1.2 to pH 13.5) and in conditions lacking given nutrient. They were tolerant of concentrations of Fe(II) up to 50mM and grew better with low oxygen levels (1.6%) than without.


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