Anaerobic co-fermentation of straw and manure is a potential technique for biogas production. In this process

the spatial and temporal dynamics of prokaryotes associated to straw and sludge

and their correlations with bioreactor performance remain to be unveiled. To address these questions

prokaryotic compositions and dynamics associated to straw and sludge were investigated during co-fermentation of straw and swine manure using pyrosequencing technique. Co-fermentation of straw and swine manure contributed significantly to fermentation performance. Further analysis indicated that spatial distribution pattern of prokaryotes in the co-fermentation system might increase fermentation efficiency. Straw was digested by its associated microbiota

such as genera Treponema

Clostridium Ⅲ

Alkaliflexus and Fibrobacter

providing substrates for the production of volatile fatty acids (VFAs). Propionic acid was most abundant in the sludge. The genera Syntrophomonas

Pelotomaculum

Methanoculleus

Methanosarcina and Methanosaeta metabolize VFAs into methane syntrophically via both hydrogenotrophic and acetocalstic pathways. The genera Aminobacterium and Cloacibacillus involved in amino acid degradation were much abundant in the sludge

indicating that protein was an important substrate for methanogenesis. These findings suggested that spatial distribution of microbiota

steady straw-associated degraders and dynamic microbial communities in the sludge were vital for the performance of biogas co-fermentation system.