16S rRNA Metagenomics of Gut Microbiota of Male Wistar Rats Fed with Genetically Modified Cowpea

The gut microbiota is an important component of host physiology, contributing to nutrient metabolism, intestinal homeostasis, immune regulation and maintenance of the gut environment. Genetically modified Bt cowpea expressing a Bacillus thuringiensis insecticidal protein provides an important approach for controlling cowpea pod borer and improving cowpea production. However, evaluation of its potential influence on the intestinal microbial community is relevant to the assessment of its biological effects following dietary exposure. This study investigated the effect of dietary consumption of genetically modified Bt cowpea on the gut microbiota of male Wistar rats using 16S rRNA metagenomic analysis. Adult male Wistar rats were acclimatized and allocated to control, 50% Bt cowpea and 100% Bt cowpea dietary groups and maintained on the respective diets for 16 weeks. At the end of the feeding period, faecal samples were collected from two rats in each group, pooled within treatment groups and subjected to bacterial DNA extraction and 16S rRNA metagenomic analysis. The kingdom-level analysis showed that bacterial sequences constituted 73.1% of the classified reads in the control group, 57.1% in the 50% Bt cowpea group and 51.1% in the 100% Bt cowpea group, while unassigned sequences increased from 26.9% in the control to 42.9% and 48.9% in the 50% and 100% Bt cowpea groups, respectively. Species-level analysis demonstrated distinct taxonomic profiles among the dietary groups. The control group was characterized principally by Lactobacillus acidophilus (9.7%), Cryptobacterioides sp000431015 (8.5%), Blautia sp028767025 (8.2%), Lactobacillus intestinalis (5.6%) and Limosilactobacillus reuteri (4.9%). In the 50% Bt cowpea group, the predominant taxa were Lactobacillus sp947171515 (16.1%), Limosilactobacillus reuteri (11.4%), Lactobacillus intestinalis A (11.2%) and Duncaniella sp910576785 (11.2%). In contrast, the 100% Bt cowpea group was characterized predominantly by Cryptobacterioides sp000433355 (9.3%), Victivallis vadensis (6.0%), Prevotella faecis (5.9%), Phascolarctobacterium sp94392035 (5.6%), Treponema D berlinense (4.9%) and Vescimonas sp00043555 (4.7%). These findings demonstrate dose-associated differences in the taxonomic composition of the gut bacterial community following Bt cowpea exposure. The increased representation of Lactobacillus and Limosilactobacillus in the 50% Bt cowpea group, together with the emergence of Prevotella, Phascolarctobacterium and Victivallis among the predominant taxa at 100% Bt cowpea exposure, suggests dietary modulation of the intestinal microbial ecosystem. Such changes are biologically plausible because dietary composition, particularly the availability of fermentable carbohydrates and dietary fibre, is a major determinant of gut microbial composition and function (Delzenne et al., 2025; Ross et al., 2024). The study provides preliminary evidence that prolonged consumption of Bt cowpea is associated with alterations in the taxonomic structure of the gut microbiota of Wistar rats and supports the need for further studies using individually analysed animals, appropriate non-GM cowpea controls and functional microbiome measurements.