How is nitrogen from the atmosphere, the biotic part of the ecosystem, converted in to the biotic part of the ecosystem in organisms?

In the process of the nitrogen cycle.                

The nitrogen cycle is a biogeochemical succession process of nitrogen that involves: fixation, ammonification, nitrification, and denitrification. Like any other biogeochemical cycles. This process undergoes and affects the biological, geometrical and chemical aspects in the ecosystem and the abiotic and biotic community. Hence, the nitrogen cycle leads the abiotic component –nitrogen- to contribute to the biotic community, decomposition and primal production. Further, it becomes an essential part of the environment because some life components are contains it, similarly, amino acids, nucleic acids in RNA and DNA.  

Explanation:

These are both  microscopic, unicellular organisms of no cell organelles; that is they lack the basic organelles of cells like the mitochondria, endoplasmic reticulum, nucleus etc.Their genetic materials are conserved in a single circular chromosomes, unlike in eukaryotes where they are packed   in nucleus. Other similarities are:

Both  are Prokaryotes.

They both lack nucleus

They both lack membrane bound organelles.

They both undergo reproduce asexually by  binary fission.

Both also have plasma membranes.

Explanation: