Award Date

August 2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Science

First Committee Member

Michelle M. Elekonich

Second Committee Member

Ernesto Abel-Santos

Third Committee Member

Helen Wing

Fourth Committee Member

Penny Amy

Fifth Committee Member

Martin Schiller

Sixth Committee Member

Jefferson Kinney

Number of Pages

158

Abstract

Honey bee (Apis mellifera) pollination plays an important role in meeting our agricultural needs, yet we are incapable of completely preventing a decline in bee health, partially due to bacterial diseases. American Foulbrood (AFB), a bacterial disease of honey bee larvae, is particularly troublesome because the infectious agent is the bacterial spore of Paenibacillus larvae. Bacterial spores are resistant to extreme temperatures, unaffected by antibiotics, withstand exposure to disinfectants, and can remain dormant for years until they can revert back to vegetative cells.

Our research investigated P. larvae spore germination at the functional and pathogen-host level. We have found that P. larvae spores exit dormancy after exposure to an L-tyrosine plus uric acid solution. Germinated P. larvae spores were susceptible to killing with heat that would normally not affect dormant spores. These data suggest how triggering spore germination could help in decontamination of P. larvae spores in bee hives. We identified indole and phenol as inhibitors of P. larvae spore germination in vitro. Additional compound screens identified other indole analogs that inhibited P. larvae spore germination. These compound screens probed the binding pocket(s) of the P. larvae germination receptor machinery. We identified compounds that interacted with the germination receptor(s) and blocked L-tyrosine plus uric acid spore germination. We also tested the effect of germination inhibitors on honey bee larvae. Larvae fed germination inhibitors had similar survival to the control groups. We found that prophylactic treatment with germination inhibitors prevented AFB disease in laboratory reared larvae. Lastly, we measured mRNA levels for the putative GerKA and PrkC germination receptors found in P. larvae spore. Two GerKA germination receptor mRNAs were found to be upregulated during sporulation. Our findings are relevant to beekeeping industry and a wide scientific audience because the spore germination is the first step in establishment of several diseases.

Keywords

American; Bee; Foulbrood; Germination; Larvae; Spore

Disciplines

Biochemistry | Biology

Language

English


Share

COinS