The bacteria are the most beneficial for humans.

There are more types of bacteria that are beneficial to humans. First of all, these are the bacteria that live in our intestines. They help us break down fiber. Also, cyanobacteria are very important, which provide our atmosphere with oxygen. Lactic acid bacteria allow us to ferment various vegetables and get such products as sour cream, kefir and so on. Also, decay bacteria are important, which provide the cycle of substances in nature. Thanks to them, life has existed for about 4 billion years on our planet.