They fix nitrogen from dinitrogen (N2) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis. Nitrogenase is inactivated by oxygen, so the heterocyst must create a microanaerobic environment.
Vitamin B12 is an especially important vitamin for maintaining healthy nerve cells, and it helps in the production of DNA and RNA, the body's genetic material. Vitamin B12 works closely with vitamin B9, also called folate or folic acid, to help make red blood cells and to help iron work better in the body.
Subcutaneous B-12 injections may be less painful than intramuscular ones. Your body uses vitamin B-12 to make red blood cells, nerves, DNA and protein. B-12 also helps your body metabolize fat and carbohydrates for energy. Although your body is unable to generate B-12, the vitamin is readily available from dietary sources including dairy, meat and fish. If you develop a vitamin B-12 deficiency, intramuscular or subcutaneous injections may be necessary.