Community 3 1. Guild 1: methanogenic bacteria(C02-+CH4) homoacetogenic bacteria(CO,-> acetate) 2. Guild 2: sulfate-reducing bacteria (SO4 -+H2S) sulfur-reducing bacteria(S-+H2S) 3. Guild 3: denitrifying bacteria(NO3-+ N2) ferric iron-reducing bacteria(Fe-+Fe 4. Guild 4: fermentative bacteria (fermenting sugars amino and fatty acids, and so on) Community 3 SedimentsCommunity 3