Nutrient–Microbiota Co-Regulation of Protein Conversion in Black Soldier Fly Larvae: The Role of Alkali-Soluble Protein and Gut Microbial Communities

Insect protein farming provides sustainable advantages in land efficiency, emission reduction, and bioconversion. A major challenge is optimizing nutrient composition to achieve cost-effective protein production. This study investigates the co-regulatory mechanism between alkali-soluble protein (SpA) and gut microbiota in black soldier fly larvae (Hermetia illucens) and their effect on protein conversion efficiency. Feeding trials with varying alfalfa/SpA ratios, a wheat middlings/alfalfa meal blend at a 5:0 ratio was identified as optimal for promoting larval protein accumulation. SDS-PAGE and 16S rRNA analyses revealed a strong positive correlation with larval crude protein (R²=0.82). Network analysis confirmed positive correlations among SpA, larval protein, Enterococcus (51%), and Ignatzschineria (44%) (p