What is the chemical nature of biogas? Name an organism which is involved in biogas production.

(N/A) Biogas is a mixture of gases,primarily composed of methane $(CH_4)$,carbon dioxide $(CO_2)$,and traces of hydrogen $(H_2)$,hydrogen sulfide $(H_2S)$,and nitrogen $(N_2)$.
Methanogens,such as $Methanobacterium$,are the microorganisms involved in the production of biogas. These bacteria grow anaerobically on cellulosic material and produce large amounts of methane along with $CO_2$ and $H_2$.