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Role of the intestinal microbiome in polyethylene degradation by caterpillar larva of the greater wax moth (Galleria mellonella)

Citation

LeMoine, Christophe et al. (2020), Role of the intestinal microbiome in polyethylene degradation by caterpillar larva of the greater wax moth (Galleria mellonella), Dryad, Dataset, https://doi.org/10.5061/dryad.2fqz612kk

Abstract

Recently, a few insects, including the caterpillar larva of the greater wax moth Galleria mellonella, have been identified as avid "plastivores". Interestingly, these caterpillars are able to ingest and metabolize polyethylene at unprecedented rates. While it appears that G. mellonella plays an important role in the biodegradation process, the contribution of its intestinal microbiome remains poorly understood and contested. In a series of experiments, we present strong evidence of an intricate relationship between an intact microbiome, low density polyethylene (LDPE) biodegradation, and the production of glycol as a metabolic by-product. First, we biochemically confirmed that G. mellonella larvae consume and metabolize LDPE, as individual caterpillars fed on polyethylene excreted glycol, but those excretions are reduced by antibiotic treatment. Further, while the gut bacterial communities remain relatively stable regardless of diet, we show that during the early phases of feeding on LDPE (24-72 hrs), caterpillars exhibit increased microbial abundance relative to those starved or fed on their natural honeycomb diet. Finally, by isolating and growing gut bacteria with polyethylene as their exclusive carbon source for over one year, we identified microorganisms in the genus Acinetobacter that appear to be involved in this biodegradation process. Taken collectively, our study indicates that during short term exposure, the intestinal microbiome of G. mellonella is intricately associated with polyethylene biodegradation in vivo.

Methods

This dataset represents experiments exploring the role of Galleria mellonella microbiome in polyethylene degradation.

1- Glycol quantity: Galleria mellonella larvae were treated with broad spectrum antibiotic and fed polyethylene or their honeycomb diet, and we monitored glycol excretion as a metabolic by-product of polyethylene degradation.

2-Antibiotic effect: Using qPCR we established the relative microbial abundance in Galleria mellonella after 24 hours.

3-Excreta and Bacterial Abundance: Using qPCR we quantified microbial abundance (16S) of Galleria mellonella fed on polyethylene that excreted vs. did not excrete glycol.

4-Treatment Bacterial Abundance: We monitored bacterial abundance in waxworms under 3 feeding regimes: honeycomb, polyethylene and starvation for 24 and 72h.

Funding

Natural Sciences and Engineering Research Council of Canada