| Bacterial strain | Source |
| Lactobacillus acidophilus ATCC 4356 | Hardy Diagnostics |
| Lactobacillus casei ATCC 334 | Hardy Diagnostics |
| Lactobacillus rhamnosus GG (LGG) ATCC 53103 | Commercial probiotic supplement |
| Lactobacillus casei (a proprietary strain, designated as LcS in this study) | Commercial probiotic drink |
| Bifidobacterium bifidum ATCC 11863 | Hardy Diagnostics |
| Bifidobacterium animalis ssp. animalis ATCC 25527 | Hardy Diagnostics |
| Bifidobacterium infantis 35624 | Commercial probiotic supplement |
| Bifidobacterium lactis DN173-010 | Commercial yogurt |
| Escherichia coli Nissle 1917 (ECN) | University of Rhode Island (Dr. Paul S. Cohen) |
| Bacillus coagulans GBI-30 | Commercial probiotic supplement |
| Escherichia coli (JM 101) ATCC 33876 | Hardy Diagnostics |
| Bacillus pumilus ATCC 14884 | Hardy Diagnostics |