The Galleria mellonella Hologenome Supports Microbiota-Independent Metabolism of Long-Chain Hydrocarbon Beeswax

Abstract

The greater wax moth, Galleria mellonella, degrades wax and plastic molecules. Despite much interest, the genetic basis of these hallmark traits remains poorly understood. Herein, we assembled high-quality genome and transcriptome data from G. mellonella to investigate long-chain hydrocarbon wax metabolism strategies. Specific carboxylesterase and lipase and fatty-acid-metabolism-related enzymes in the G. mellonella genome are transcriptionally regulated during feeding on beeswax. Strikingly, G. mellonella lacking intestinal microbiota successfully decomposes long-chain fatty acids following wax metabolism, although the intestinal microbiome performs a supplementary role in short-chain fatty acid degradation. Notably, final wax derivatives were detected by gas chromatography even in the absence of gut microbiota. Our findings provide insight into wax moth adaptation and may assist in the development of unique wax-degradation strategies with a similar metabolic approach for a plastic molecule polyethylene biodegradation using organisms without intestinal microbiota. The evolutionarily expanded long-chain fatty acid degradation gene products of Galleria mellonella decompose long-chain hydrocarbons independently of intestinal microorganisms. Kong et al. show that beeswax and degradation products are detected equally in larvae in the presence or absence of intestinal microbes.