Self-contained synthetic E. coli resistant to viral infection could prove invaluable to the biotechnology industry by increasing product consistency and reducing safety concerns.
Tortoise leaf beetles enjoy the protection the fungus provides from insect predators such as ants, then carry the microbe to a mutual plant host, which their fungal symbiont infects.
All multicellular creatures interact with bacteria, but some have taken the relationship to another level with highly specialized structures that house, feed, and exploit the tiny organisms.