Why would life on earth not be possible without the activity of bacteria?

Bacteria take part in many processes and without them life on Earth is impossible.
So bacteria are:
– cleaners – take part in the decay processes, treating dead organic matter to inorganic matter. Without this process, the Earth would be covered with a thick layer of dead matter;
– bacteria create inorganic substances for plant nutrition, without them the plants would have died out;
– bacteria are a link in food chains;
– bacteria help digestion in animals, including humans;
– bacteria are used by humans. For example lactic acid bacteria.