anaerobic digester involves a four-staged cooperative action performed by different microorganisms. the first stage is the hydrolysis of insoluble polymerized organic matter by anaerobes such as streptococcus and enterobacterium. in the second stage, acidogens break down dissolved organic pollutants in wastewater to fatty acids. in the third stage, acetogens convert fatty acids to acetates. in the final stage, methanogens metabolize acetates to gaseous methane. the byproduct methane leaves the aqueous layer and serves as an energy source to power wastewater-processing within the digestor, thus generating a self-sustaining mechanism. methanogens also effectively decrease the concentration of organic matter in wastewater run-off. for instance, agricultural wastewater, highly rich in organic material, has been a major cause of aquatic ecosystem degradation. the chemical imbalances can lead to severe ramifications such as eutrophication. through anaerobic digestion, the purification of wastewater can prevent unexpected blooms in water systems as well as trap methanogenesis within digesters. this allocates biomethane for energy production and prevents a potent greenhouse gas, methane, from being released into the atmosphere. the organic components of wastewater vary vastly. chemical structures of the organic matter select for specific methanogens to perform anaerobic digestion. an example is the members of methanosaeta genus dominate the digestion of palm oil mill effluent (pome) and brewery waste. modernizing wastewater treatment systems to incorporate higher diversity of microorganisms to decrease organic content in treatment is under active research in the field of microbiological and chemical engineering. current new generations of staged multi-phase anaerobic reactors and upflow sludge bed reactor systems are designed to have innovated features to counter high loading wastewater input, extreme temperature conditions, and possible inhibitory compounds. strains methanobacterium bryantii methanobacterium formicum methanobrevibacter arboriphilicus methanobrevibacter gottschalkii methanobrevibacter ruminantium methanobrevibacter smithii methanococcus chunghsingensis methanococcus burtonii methanococcus aeolicus methanococcus deltae methanococcus jannaschii methanococcus maripaludis methanococcus vannielii methanocorpusculum labreanum methanoculleus bourgensis (methanogenium olentangyi and methanogenium bourgense) methanoculleus marisnigri methanoflorens stordalenmirensis methanofollis liminatans methanogenium cariaci methanogenium frigidum methanogenium organophilum methanogenium wolfei methanomicrobium mobile methanopyrus kandleri methanoregula boonei methanosaeta concilii methanosaeta thermophila methanosarcina acetivorans methanosarcina barkeri methanosarcina mazei methanosphaera stadtmanae methanospirillium hungatei methanothermobacter defluvii (methanobacterium defluvii) methanothermobacter thermautotrophicus (methanobacterium thermoautotrophicum) methanothermobacter thermoflexus (methanobacterium thermoflexum) methanothermobacter wolfei (methanobacterium wolfei) methanothrix sochngenii