Methanosarcina domination in anaerobic sequencing batch reactor at short hydraulic retention time

• ASBR has potential to establish a Methanosarcina dominated methanogenic community.
• Microbial community showed higher diversity when reactor performance was superior.
• Homoacetogenesis plus aceticlastic methanogenesis was speculated as main pathway.
• 16S rRNA or mcrA clone library alone cannot provide complete community structure.

The Archaea population of anaerobic sequential batch reactor (ASBR) featuring cycle operations under varying hydraulic retention time (HRT) was evaluated for treating a dilute waste stream. Terminal-Restriction Length Polymorphism and clone libraries for both 16S rRNA gene and mcrA gene were employed to characterize the methanogenic community structure. Results revealed that a Methanosarcina dominated methanogenic community was successfully established when using an ASBR digester at short HRT. It was revealed that both 16S rRNA and mcrA clone library could not provide complete community structure, while combination of two different clone libraries could capture more archaea diversity. Thermodynamic calculations confirmed a preference for the observed population structure. The results both experimentally and theoretically confirmed that Methanosarcina dominance emphasizing ASBR’s important role in treating low strength wastewater as Methanosarcina will be more adept at overcoming temperature and shock loadings experienced with treating this type of wastewater.

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