Kämpfer, PeterCifuentes Triana, Yina AlejandraYina AlejandraCifuentes Triana2025-08-132025-08-132025https://jlupub.ub.uni-giessen.de/handle/jlupub/20755https://doi.org/10.22029/jlupub-20105Understanding the interplay between Hermetia illucens larvae and their gut microbiome is essential for harnessing these insects in waste management and animal feed production. This investigation assessed the bacterial communities within the larval gut and the accompanying feed residue throughout the rearing process. The findings indicate that the larval gut maintains a stable core microbiome comprising genera such as Dysgonomonas, Morganella, Enterococcus, Providencia, and Klebsiella, with high strain-level diversity that may underline the larvae’s adaptability to various substrates. In contrast, the feed residue exhibits marked shifts in the bacterial composition during rearing, including a significant reduction in potential pathogenic taxa. Dynamic changes in antibiotic and disinfectant resistance genes were observed: the methicillin resistance gene (mecA ), initially prevalent in the residue, was reduced over time; the β-lactamase gene (blaSHV) remained consistently present in the larval gut but disappeared from later residue samples; and while quaternary ammonium compound resistance genes (qacE/qacEΔ1) were absent from the gut; their abundance increased in the residue. Additionally, the sulfonamide resistance gene (sul2) showed a significant increase in the residue, whereas tetracycline resistance gene (tetM) levels remained constant across both matrices. Furthermore, the use of both dilution-to-extinction- and direct plating cultivation methods facilitated the isolation of 18 distinct phylotypes, revealing a high genetic diversity within key genera such as Providencia, Enterococcus, and Morganella. These results underline the complexity of microbial dynamics during H. illucens rearing and highlight potential environmental concerns regarding the dissemination of resistance genes through organic waste. In summary, the findings elucidate the intricate microbial dynamics present during H. illucens rearing. The resilience and diversity of the larval gut microbiome contrast with the substantial compositional and functional changes observed in the feed residue. Moreover, the documented shifts in antibiotic- and disinfectant resistance gene profiles highlight the potential environmental implications that warrant further investigation. These insights provide a foundation for the rational design of bioconversion processes and the optimization of strategies ensuring an improved microbiological safety of animal feed products.enIn CopyrightBlack soldier flyCore gut microbiotaCultivation approachDilution-to-extinctionDirect platinggenomic fingerprintingHermetia illucensAntibiotic resistance genesDisinfectant resistance genesFeed residue microbiomeGut microbiomeMicrobiome analysisQuantitative PCRddc:500ddc:630