In: Biology
We can't live without bacteria because bacteria plays a major role in our life by participating in various metabolic activities and even plays a key role in the immune system. A person who is microbes-free had entered into the bubble of world that is moving with bacteria can't survive because their immune system can't support that, so life cannot exist without bacteria. When coming to oxygen revolution, the oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Era. The earth's atmosphere before that time was of a different chemistry and unsuitable for life as we know it. Cyanobacteria was the first organisms that used H2O instead of H2S or some other compounds as a source of electrons and hydrogen to the carbondioxide fixation. They were able to synthesize organic compounds from water and carbon dioxide by releasing oxygen as a by-product of their photosynthesis they affect changed the earth's atmosphere. In endosymbiosis, firstly endosymbionts are the organisms that form a symbiotic relationship with another cell or organism. Endosymbiotic bacteria mainly helps in the fixing of nitrogen for their diatom hosts and in turn receive organic carbon from photosynthesis. These symbioses play an important role in the global carbon cycling in oligotrophic regions. Eg: Rhizobium plants. In nitrogen fixation bacteria plays an important role. Nitrogen fixing bacteria are the microorganisms that are present in the soil or in plant roots that change nitrogen gases from the atmosphere into solid nitrogen compounds that plants can use in the soil ( nitrifying and denitrifying processes).