Modulation of the Fecal Microbiota in Sprague-Dawley Rats Using Genetically Modified and Isogenic Corn Lines

A 7-year feed study on the long-term effects of genetically modified maize containing cry1Ab/cry2Aj and EPSPS genes on gut microbiota and metabolite profiles across two generations of cynomolgus macaques

The health implications of genetically modified (GM) crops remain controversial relative to their non-GM counterparts, particularly regarding long-term dietary exposure. Although the gut microbiome is a key health indicator, studies investigating the impact of GM crop consumption on intestinal microbiota remain limited. This study presents a comprehensive 7-year evaluation of GM maize expressing cry1Ab/cry2Aj and G10evo-EPSPS proteins through metagenomic and metabolomic analyses. We assessed the effects of GM maize consumption on gut microbiota diversity and metabolite profiles in cynomolgus macaques (Macaca fascicularis) compared with non-GM maize. Three diet regimens were implemented: a conventional compound feed (CK group), diet formulation containing 70 % non-GM maize (Corn group), and diet formulation containing 70 % GM maize (Tg group). The results demonstrated that feeding GM maize to the first (F0) and second (F1) generations of monkeys did not substantially affect the composition, community structure, or function of the intestinal microbiome, as indicated by species composition and diversity analyses. Minor differences in intestinal metabolites were observed but were not directly linked to transgenic maize consumption. Collectively, long-term intake of maize with cry1Ab/cry2Aj and g10evo-epsps genes had no adverse effects on macaques or their offspring.

Multigenerational effects of cultivating transgenic maize straw on earthworms: A combined laboratory and field experiment

The cultivation of genetically modified (GM) maize has aroused notable public concern related to the potential risks to soil fauna caused by the release of foreign proteins. In this study, the potential effects of cultivating the GM maize variety DBN9936, which exhibits the expression of the Cry1Ab and EPSPS proteins, on earthworms (Eisenia fetida) were evaluated under laboratory and field conditions. No significant differences in the survival, body weight, cocoon production, or hatching of earthworms fed GM or non-GM DBN318 maize were detected after three consecutive generations in a laboratory test. The enzymatic activity assay results revealed no significant differences in superoxide dismutase (SOD) or catalase (CAT) enzyme activity between the GM and non-GM maize varieties. Furthermore, exogenous Cry1Ab and EPSPS proteins were undetectable in the gut tissues of earthworms raised with GM maize straw. GM maize cultivation imposed no adverse effects on the species composition or density of soil earthworms in the two consecutive years during the field test, and the soil earthworm species, total number of earthworms and density of each earthworm species did not significantly differ between the GM maize and non-GM maize lines. On the basis of our findings, we concluded that the cultivation of the GM maize variety DBN9936 does not pose a risk to earthworms.

Comparative characterization of bacterial communities in geese consuming of different proportions of ryegrass

Geese are extremely well-adapted to utilizing plant-derived roughage in their diet, so the grass must be added to commercial diets under intensive rearing systems. However, it is unclear whether the gut microbiota will change significantly when adding different proportions of ryegrass. In this study, 240 healthy male Yangzhou geese (28 days old) with similar body weights were randomly divided into four groups and fed different proportions grass (CK, whole commercial diets; EG1, ryegrass: commercial diets = 1.5:1; EG2, ryegrass: commercial diets = 2:1; EG3, ryegrass: commercial diets = 3:1) respectively. When the geese grew to 70 days old, their intestines were collected and high-throughput sequencing technology was performed to investigate the microbial diversity in the caecum of geese with different dietary supplements. There was no obvious change in the alpha diversity of gut microbiota of geese with ryegrass intake (P > 0.05) and the composition of dominant bacterium (including Bacteroidetes and Firmicutes) was also similar. However, the ratio between Firmicutes and Bacteroidetes was remarkably reduced with ryegrass intake (P < 0.05), and the relative abundance of 30 operational taxonomic units (OTUs) significantly differed. Additionally, the content of cellulose-degrading microbiota such as Ruminiclostridium and Ruminococcaceae UCG-010 were significantly increased in geese fed with increasing amounts of grass. Finally, the functional profiles of the goose gut microbiota were explored using the PICRUSt tool. Carbohydrate metabolism and amino acid metabolism were dominant metabolic pathways. Lipid metabolism was significantly increased in EG3 compared that in the CK group (P < 0.05). Interestingly, Turicibacter and Parasutterella may have affected abdominal fat deposition as grass intake increased. Taken together, although the diversity of bacterial communities was similar in geese fed with different proportions of ryegrass, cellulose-degrading microbiota (Ruminiclostridium and Ruminococcaceae UCG-010) were abundant and the lipid metabolic pathway was enriched, which may reduce abdominal fat accumulation in high-ryegrass fed geese.

The Chronic Effect of Transgenic Maize Line with mCry1Ac or maroACC Gene on Ileal Microbiota Using a Hen Model

The experiment was to determine the chronic effects of two transgenic maize lines that contained the mCry1Ac gene from the Bacillus thuringiensis strain (BT) and the maroACC gene from Agrobacterium tumefaciens strain (CC), respectively, on ileal microbiota of laying hens. Seventy-two laying hens were randomly assigned to one of the three dietary treatments for 12 weeks, as follows: (1) nontransgenic near-isoline maize-based diet (CT diet), (2) BT maize-based diet (BT diet), and (3) CC maize-based diet (CC diet). Ileum histological examination did not indicate a chronic effect of two transgenic maize diets. Few differences were observed in any bacterial taxa among the treatments that used high-throughput 16S rRNA gene sequencing. The only differences that were observed for bacterial genera were that Bifidobacterium belong within the Bifidobacteriaceae family tended to be greater (p = 0.114) abundant in hens fed the transgenic maize-based diet than in hens fed the CT diet. Birds that consumed the CC maize diet tended to have less abundance (p = 0.135) of Enterobacteriaceae family in the ileum than those that consumed the CT maize diet. These results indicate the lack of adverse effects of the BT maize and the CC maize lines on the ileal microbiota of hens for long term and provide important data regarding biosafety assessment of the transgenic maize lines.