The reason they can survive is because they are autotrophs, organisms that synthesize organic compound from inorganic sources. Scientists estimate some microbial communities to be millions of years old. Of the small percentage of microorganisms that have been examined, a large amount of them have shown valuable capabilities, such as, the ability to degrade toxic organic compounds, the production of antibiotics, heat stable enzymes and novel pigments. Many positive results will surely come from these microorganisms. They may even show us how life functioned before photosynthesis evolved.
Microorganisms are essential for all life because they decompose waste.
If it were not for decomposers, elements that are essential to life would be locked up in dead animals and feces. Plants use the energy from the sun to feed themselves through the environment with carbondioxide, water, and mineral nutrients in the soil. Some of these mineral nutrients are not readily obtainable by plants through the ecosystem, but are essential for plants and animals. Decomposer bacteria are the only organisms that can transform nonbiological material such as nitrogen, iron, and sulfur to be obtainable to other organisms. Nitrogen released by bacteria is used by plants to form amino acids, and proteins, which are essential for life.