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

As demand for sustainable protein sources grows, edible insects like <i>Tenebrio molitor</i> (yellow mealworm) are gaining attention as functional feed ingredients. This study investigated how dietary inclusion of <i>T. molitor</i> 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% <i>T. molitor</i> 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 sequencing. Bioinformatic analyses evaluated microbial diversity and predicted functions. Rats fed <i>T. molitor</i> 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., <i>Eubacterium coprostanoligenes</i>, Oscillospiraceae, Ruminococcaceae), and a decline in fiber- and mucin-degrading bacteria like <i>Akkermansia</i> 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 <i>T. molitor</i> meal supports a safe, functional adaptation of gut microbiota to high-protein, chitin-rich diets, supporting its potential use in monogastric animal nutrition.