Hello Elham Jamaat

You may use the colonic mucus layer of rat.

The gut microbiome adheres to mucus. Compared with the small intestine, the colonic epithelium is covered by mucus layers composed of a firm inner layer and loose outer layer that function to separate microbes from epithelial cells, and provide a diffusion barrier to maintain a balanced community. The outer mucus layer is colonized with an abundance of commensal microbes, while the inner layer is relatively sterile.

Best.