activated sludge metagenome Raw sequence reads. activated sludge metagenome

For evaluating the effect of granular structure on methanogenesis from typical methanogenic precursors, batch reactors are inoculated with intact and disintegrated granules using formate, hydrogen, or acetate as the sole substrate and incubated at 37±1°C. Methane production is simulated using a modified Gompertz model. Kinetics results revealed that the methanogenesis rate order during the first generation in different sludge systems was Uformate > UH2/CO2> Uacetate, indicating that formate consumption has an advantage over hydrogen in studied granular system. This means that interspecies formate transfer might be more preferable compared to interspecies hydrogen transfer and the importance of interspecies formate transfer in granular sludge might have been underestimated in previous studies. In addition, the physical structure of the sludge had a significant impact on the methanogenesis rate of formate and hydrogen, while has little impact on acetate methanation rate. By considering both the microbial community and kinetics results, it was found the physical structure of sludge influenced a shift in microbial communities in formate and H2 added systems and further affected the activity of formate and hydrogen in studied system. This study enlightens us that though it was difficult to identify the relative importance of interspecies formate and hydrogen transfer directly, we could find out the preferable interspecies electron carrier by applying the method described in this research, and further regulating the anaerobic digester in practice.