Microbial drivers of Black Soldier Fly biowaste valorization: from microbiome functions to scalable insect-microbe systems.

Biowaste and agro-industrial co-products continue to increase with population growth and rising living standards, calling for scalable valorization strategies that go beyond simple mineralization. The black soldier fly (BSF) has emerged as a practical bioconversion platform capable of channeling biodegradable organic waste into high-value proteins, lipids, and chitin. In parallel, microbial interventions are increasingly recognized as key levers for substrate conditioning, process stabilization, and performance optimization in BSF-based systems. In this review, we adopted a function-first perspective to examine how microbial processes shape and connect three major biological valorization routes: aerobic composting, anaerobic digestion (AD), and BSF bioconversion. Rather than focus on taxonomic inventories, we synthesized evidence on microbial functions that matter in practice, including extracellular hydrolysis of complex polymers, regulation of short-chain fatty acids, detoxification and pathogen suppression, and process stabilization. We further reviewed microbe-assisted strategies, such as lactic pre-fermentation, directed acidogenesis, and probiotic or defined consortia and their effects on waste reduction, conversion efficiency, product quality, and sanitary safety. Finally, we translated these microbial mechanisms into scalable design principles for configuring and operating integrated insect-microbe systems, highlighting how microbial functions underpin reproducible, enterprise-ready performance across composting, AD, and BSF-integrated workflows.