What is the role of bacteria in the nitrogen cycle?

THe bacteria that lives in the nodules of legumes are the only ones able to fix nitrogen gas into ammonia, which is later fixed by other bacteria in the soil to nitrites and nitrates that the plants can use.

some bacteria also performs denitrification, which converts ammonia back to  nitrogen gas, allowing the cycle to continue

The infrared (ir) and the ultraviolet(uv) represent the two extremities of the visible spectrum (400-700nm). while ir represents electromagnetic radiation with wavelengths longer than those of visible light, uv represents wavelengths shorter than visible light