Microbial fermentation and black soldier fly feeding to enhance maize straw degradation.

This study used an innovative synergistic microbial and insect approach to treat maize straw and kitchen waste substrates, including cyclic microbial fermentation and feeding of black soldier fly larvae (BSFL) using the fermented substrate. Increasing cycle numbers led to significantly increased cellulose, hemicellulose, and lignin degradation rates (DR) in the maize straw, which increased by 68.28%, 81.43% and 99.95%, respectively, compared to those in the blank group without frass addition. Moreover, according to the experimental results, it was revealed that the structure of lignocellulose, the composition and structure of the bacterial community in the BSFL gut and frass changed significantly after the addition of the previous cycle of frass treatment. Moreover, the differences in amplicon sequence variants (ASVs) between the gut and frass further increased. The relative abundances of Enterococcus and Actinobacteria in the gut and Gammaproteobacteria_unclassified and Dysgonomonas in the frass increased significantly, which may play a more positive role in lignocellulose degradation. In conclusion, this study showed that frass fermentation + BSFL feeding to degrade straw is a promising method and that frass fermentation is beneficial for the whole cycle. Furthermore, these findings underscore the beneficial impact of frass fermentation on the entire cycle.