Tenebrio molitor Meal-Induced Changes in Rat Gut Microbiota: Microbiological and Metagenomic Findings

As demand for sustainable protein sources grows, edible insects like Tenebrio molitor (yellow mealworm) are gaining attention as functional feed ingredients. This study investigated how dietary inclusion of T. molitor meal affects gut microbiota composition and diversity in laboratory rats. Wistar rats were divided into three diet groups: standard feed, 35% chicken meal, and 35% T. molitor meal. Fecal samples were collected at weeks 4, 6, and 8. Microbial populations were assessed using culture-based methods, and community structure was analyzed at week 9 via Illumina MiSeq 16S rRNA and ITS sequencing. Bioinformatic analyses evaluated microbial diversity and predicted functions. Rats fed T. molitor meal showed significantly reduced counts of total aerobic/anaerobic bacteria, fungi, and coagulase-positive staphylococci. Metagenomics revealed a Firmicutes-dominated microbiota, with enrichment of protein- and cholesterol-metabolizing taxa (e.g., Eubacterium coprostanoligenes, Oscillospiraceae, Ruminococcaceae), and a decline in fiber- and mucin-degrading bacteria like Akkermansia and Muribaculaceae. Functional predictions indicated upregulated amino acid metabolism and chitin degradation. Despite compositional shifts, microbial diversity remained stable, with no signs of dysbiosis. These findings suggest that T. molitor meal supports a safe, functional adaptation of gut microbiota to high-protein, chitin-rich diets, supporting its potential use in monogastric animal nutrition.