Identifier

etd-07052017-135908

Degree

Doctor of Philosophy (PhD)

Department

Entomology

Document Type

Dissertation

Abstract

The Formosan subterranean termite (FST), Coptotermes formosanus, is an invasive urban pest in the United States. Colonies of the FST are dependent on the symbiotic gut protozoa for cellulose digestion in the workers’ guts, and the gut bacterial community is known to provide essential nutrients to the termite. The objectives of this PhD research were to develop and evaluate paratransgenesis and phage therapy for termite control. During this study, a termite gut bacterium: Trabulsiella odontotermitis was genetically engineered and was evaluated as a ‘Trojan horse’ for paratransgenesis. We proved that T. odontotermitis can tolerate 50 times more concentration of ligand-Hecate than the concentration required to kill the gut protozoa. We also engineered T. odontotermitis to express Green Fluorescent Protein (GFP) and visualized the expression of GFP in the termite gut. We created a strain of T. odontotermitis expressing kanamycin-resistant gene using tn7 transposon. We used this strain to prove that once ingested, T. odontotermitis can stay in the termite gut for at least three weeks and it is horizontally transferred amongst nest mates. We also engineered T. odontotermitis to express functional ligand-Hecate-GFP fusion protein. Removal of the bacterial community from the gut also has a negative impact on the survival of the termites. The presence of a diverse and rich bacterial community makes the termite gut a perfect niche for bacteriophages; viruses that infect bacteria. So far, there has been no research to study the presence and role of bacteriophages in the gut of the termite. Bacteriophages have the potential to be used in ‘Phage therapy’ targeting the essential termite gut bacteria. During this study three novel bacteriophages were isolated and sequenced from the termite gut. A meta-virome sequencing of the termite gut was also done, which revealed the presence of previously unknown bacteriophages and other viruses associated with the termites. This is the first study elucidating the presence of a diverse and largely unexplored bacteriophage community in the termite gut. The study suggests that termites can serve as a model system to study the effect of bacteriophages on bacteria and ultimately on the host harboring the microbial community.

Date

2017

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Hussseneder, Claudia

Available for download on Saturday, February 23, 2019

Included in

Entomology Commons

Share

COinS