Elucidating the potential symbiotic relationships between ciliates and bacteria

Symbiotic interactions are present in nearly every ecosystem on Earth (Zilber-Rosenberg et al., 2008; Louis, 2010; Gast et al. 2009). Though considerable work has been done on symbionts of animals and plants (Douglas, 1998; Lindquist, 1975; Peterson, 1999), less is known about symbionts of microbes. Symbiotic relationships are frequently observed between bacteria and ciliates, the latter a lineage of single-celled microbial eukaryotes (Görtz, 2001; Fenchel and Finlay, 1991; Embley et al., 1992). Hence, my thesis focuses on the potential bacterial symbionts in two understudied ciliate genera, Loxodes and Blepharisma. My goal is to understand symbiotic relationships between ciliates and bacteria by identifying bacterial symbiotic candidates that live within the ciliates. By studying these symbiotic relationships, we can learn more about how organisms may have evolved to exploit their habitats. I investigated potential symbiotic relationships using bioinformatics and microscopy to identify bacterial symbiont candidates such as Caulobacter, Sphingomonas, and Bradyrhizobium. I also implemented bioinformatic and microscopic approaches, which can be used in the future to learn more about intracellular bacteria in microbial eukaryotes. By studying symbiotic relationships among microbes, we can gain insights into the biodiversity of eukaryotes and potentially learn more about vectors for disease