Bacterial dynamics during industrial rearing of black soldier fly larvae fed on plant-based food waste

The larvae of the black soldier fly (BSFL) can efficiently convert food waste into valuable biomass. They are also an alternative source of fat, protein, and chitin, but little is known about the total microbiota of the whole BSFL and its impact on the microbiological safety of food and feed. This study was conducted to determine the microbiota dynamics of the whole BSFL and frass residues during the industrial rearing process, including the impact of thermal treatment. The second and the fourth instar larvae, frozen fourth instar larvae, and frass samples were examined. The composition of the total bacterial microbiota in the second and the fourth instar BSFL was similar and dominated by Proteobacteria while in frass Firmicutes prevailed. The lowest diversity was observed in the second instar larvae and the greatest in frass. Samples showed relatively low bacterial community diversity. The findings of this work enhance scarce knowledge of the dynamics of microorganisms in the industrial-scale food waste upcycling process by BSFL.