Is there a relationship between representatives of different kingdoms? Give examples of this relationship

Is there a relationship between representatives of different kingdoms? Give examples of this relationship between animals and bacteria.

The relationship between kingdoms always exists. First of all, representatives of different kingdoms are connected to each other in food chains. Heterotrophs are capable of eating other heterotrophs and autotrophs. Organisms are also capable of making useful connections. For example: the symbiosis of fungi and plants (algae) is lichens. There is also a symbiosis between bacteria and animals. Our intestines are home to many bacteria that secrete specific digestive enzymes. Cows have about two kilograms of such bacteria in their bodies.