Investigating antimicrobial resistance in the gut bacteria of insects feeding on plants

Ignasiak, Katarzyna (2016) Investigating antimicrobial resistance in the gut bacteria of insects feeding on plants. Doctoral thesis, University of East Anglia.

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It has been previously described that antibiotic-resistant bacteria can be found in the
guts of insects feeding on a variety of plants and not exposed to significant levels of
antibiotics. Such naturally-occurring resistance has implications for clinically-relevant
antibiotic resistance, which is a worldwide problem, and for using plants as a source of
potential novel antibiotics. We investigated this phenomenon further. Firstly, we
searched for antibiotic resistance in different insects’ guts and explored its origin, using
two lepidopteran hosts feeding on artificial food containing either ciprofloxacin or
oxytetracycline. We discovered that these antibiotics have a diverse impact on the
insect gut microbiome, beyond simply inducing antibiotic resistance. Secondly, we used
the insect gut bacteria to identify plant extracts with antibacterial activity, and purified
their active fractions. We found that vindoline, from leaf extract, and serpentine, from
root extract, are the most abundant metabolites in active fractions of Madagascar
periwinkle extracts. Finally, we developed one of the insect species we used, Galleria
mellonella, into a laboratory model for antibiotic efficacy testing, toxicity testing and as
a model for human baby gut. In summary, in this project we explored different aspects
of the antibiotic resistance that can be found in the insect gut and used it to guide us
towards plant metabolites with antibacterial properties.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 06 Feb 2017 09:55
Last Modified: 06 Feb 2017 09:55


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