Microbial ecology and functional landscape of black soldier fly larval bioconversion of orange waste: A metataxonomic perspective.

The accumulation of citrus waste, particularly orange waste (OW), presents significant environmental and economic challenges in Nigeria and worldwide. This study presents the first high-resolution, species-level metataxonomic analysis of OW bioconversion mediated by black soldier fly larvae (BSFL) in a West African context, addressing a critical gap in region-specific microbial ecology. Using long-read PacBio 16S rRNA sequencing and PICRUSt2-based functional prediction, microbial communities were profiled across three ecologically distinct substrates: untreated OW, BSFL gut microbiota (OW-BSFL), and post-digestion frass (OWF). Results revealed a dramatic microbial shift driven by host filtering: the OW-BSFL metagenome was overwhelmingly dominated (> 96%) by Lysinibacillus and Cytobacillus, while OWF exhibited markedly higher diversity (263 species), including Mycolatisynbacter and Sphingobacterium. Functional analysis revealed a significant enrichment of genes associated with carbohydrate (e.g., COG2814, COG0726) and amino acid metabolism (e.g., COG1173, COG0444) in the BSFL gut, indicating an elevated enzymatic processing capacity during waste digestion. In contrast, OWF displayed unique enrichment in genes associated with residual carbohydrate turnover and environmental colonization. This microbial succession highlights the selective enrichment and functional specialization that occur across the substrate-gut-frass continuum. By elucidating keystone taxa and metabolic signatures, the study not only advances understanding of insect-microbiome symbiosis but also provides a microbial blueprint for optimizing waste-to-value strategies. The findings support the deployment of BSFL bioconversion as a scalable, sustainable solution for organic waste valorization and biofertilizer production in sub-Saharan Africa's circular bioeconomy.