The Influence of Microbial Fermentation on Growth Performance, Protein Solubility, and Lipid Modulation in the Black Soldier Fly (Hermetia illucens) Larvae

Organic waste is being generated at an increasing pace across the globe, creating an urgent need for sustainable approaches to convert organic residues into value-added bioproducts. Black Soldier Fly Larvae (BSFL, Hermetia illucens) represent an effective biotechnological solution for waste valorization due to their ability to transform organic waste into nutrient-rich biomass. This study evaluated the impacts of microbial fermentation of fruit–vegetable and kitchen waste on BSFL growth performance and nutritional composition. Substrates were fermented using protease- and cellulase-producing bacterial strains, including Bacillus subtilis (S1), Bacillus amyloliquefaciens (KSM12) previously reported from our lab, and Lactobacillus rhamnosus (FM9), and Lactobacillus fermentum (FM16) from Microbiology Research Group collection. Sixteen treatments were formulated using specific and mixed bacterial inoculations to evaluate their individual and combined effects on larval development and nutrient assimilation. The findings indicated that substrate fermentation extensively enhanced larval mass, length, survival rate, bioconversion efficiency, efficiency of conversion of ingested feed, conversion ratio, and waste reduction index compared with unfermented substrates. The nutritional value of BSFL was also increased, with increased crude protein and lipid content. Protein fraction analysis demonstrated higher levels of soluble proteins (albumins and globulins) and reduced prolamin and glutelin fractions, indicating enhanced protein digestibility. Lipid profiling by GC–MS analysis of selected groups exhibited improved medium-chain fatty acids, particularly lauric (C12:0) and palmitic (C16:0) acids. Overall, microbial fermentation of BSFL substrates boosts organic waste utilization and validates sustainable waste valorization within a circular bioeconomy, providing nutrient-rich feed components for poultry and aquaculture sectors.