Electronic Theses for Schreyer Honors College
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Do Manduca Sexta Have A Resident Microbiome?
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Area of Honors:
Bachelor of Science
James Homer Tumlinson III, Thesis Supervisor
Curtis John Omiecinski, Honors Advisor
Green Fluorescent Protein
It is unknown whether caterpillars (specifically Manduca sexta) have a resident microbiome or if the bacteria are transient. A resident microbiome would play a more significant role in aiding caterpillars with the metabolism of nutrients and toxic compounds. The current literature shows conflicting results. We hypothesized that caterpillars do indeed have a resident microbiome. To test our hypothesis, we developed three transgenic bacteria (P. putida, B. mega, and E. coli) and designed a pulse-chase feeding assay for caterpillars to determine how long bacteria can persist within Manduca sexta. We showed that the pulse-chase assay was capable of tracking transgenic bacterial persistence by fluorescent microscopy, PCR or spreading the frass on selective plates. The first series of pulse chase experiments following each strain of bacteria separately showed that it is possible for endemic bacteria to persist within caterpillars for over a week, through multiple molting events. Additionally, the bacteria persisted within the Manduca sexta colony between experiments and multiplied within the caterpillars’ guts. The second series of pulse chase experiments showed that if caterpillars molt before the bacteria have a chance to colonize the caterpillars fully, the bacteria is much less likely to persist within the caterpillar gut and can be cleared from the system. The answer to the question of whether or not bacteria can persist within caterpillars is a definitive yes. The question of whether Manduca sexta have a resident microbiome remains undecided since it is still unclear whether persistence or transiency is normal in environmental conditions.
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