methanogenesis

noun
me·​than·​o·​gen·​e·​sis | \ mə-ˌthan-ə-ˈjen-ə-səs How to pronounce methanogenesis (audio) \
plural methanogeneses\ -​ˌsēz How to pronounce methanogeneses (audio) \

Medical Definition of methanogenesis

: the production of methane especially through the action of methanogens