Biotransformation of Canola Feedstock Waste Using Brassica Pest Microbiome: Proof of Concept for Insects as Bioengineers

Glucosinolate, isothiocyanate and sinapin toxicity limits canolameal’s use as non-ruminant animal feed. Although physico-chemical methods are effective in biorefining, they often degrade heat-sensitive, high-value compounds. While monoculture microbial biorefining has been explored, the potential of insect-associated microbiomes in this context remains underexplored. Herein, we extracted the gut and frass microbiome from canola feeding larvae of Heliothis moth (HP), Cabbage white (WCF) and cabbage looper (CL). Canolameal was fermented for 1-week with their microbiome, followed by liquid chromatography-mass spectrometry (LC-MS)-assisted metabolomics analysis. Elevated branched-SCFAs 2-hydroxy butyrate and 3-hydroxy butyrate, and propionate was observed in HP and WCF ferments, respectively. Aliphatic glucosinolates and sinapins showed ≥2-fold depletion in the HP and WCF frass ferments. Among 45 major metabolic pathways, tryptophan, tyrosine, and cysteine and glutathione metabolism were the most impacting pathways, aiding biogenic amine and branched-SCFA synthesis. S-adenosyl methionine (SAM) led salvaging played a key role in amino acid recycling via mercapturate metabolism, oxidative stress handling via methionine and cysteine metabolism pathway, and sinapin metabolism through syringate degradation. These findings highlight significant role of brassica herbivore insect gut microbiomes in detoxifying and value-adding canolameal. Such microbial communities have the potential to upcycle canolameal into a nutrient-rich feed additive with gut health-promoting properties.