Bioconversion and proteolytic of Hermetia illucens pupal exuviae into functional feed additive by Bacillus amyloliquefaciens fermentation

This study aimed to convert black soldier fly pupal exuviae to functional material through Bacillus amyloliquefaciens (BA) fermentation. The fermentation was carried out in 2 steps. First, BSFP was treated by protease and then inoculated with Bacillus amyloliquefaciens Y2 trains (BA Y2) to start fermentation. Reducing sugar content, cellulose activity, and chitinase activity of FBSFP peaked after 3000 U/g protease treatment and 5 days of fermentation. Fermented black soldier fly pupal exuviae showed great antibacterial effects against Escherichia coli and better total phenols contents, reducing power, and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity than black soldier fly pupal exuviae. In black soldier fly pupal exuviae, chitooligosaccharides content was measured, while the contents of N-acetyl-chitobiose, N-acetyl-chitotriose, N-acetyl-chitopentaose, and N-acetyl-chitohexaose were higher in fermented black soldier fly pupal. In conclusion, using BA Y2 to ferment Hermetia illucens pupal exuviae is feasible and possesses potential for the production of feed additive with bioactive functions.