After my research the answer is that they are forms of electromagnetic radiation as far as I know.
Stanley Miller's experiments showed a pre-cellular life could have begun with the formation of lipids, but it should be noted that this is not necessarily true.
Explanation: Bacteria are needed in the nitrogen cycle because plants and animals cannot directly use atmospheric nitrogen. Bacteria in the roots of plants trap nitrogen and convert it to ammonia and other nitrogen compounds which plants can then use to make protein
