No evidence for major spacial differences within the microbial communities in anaerobic digestion plants under different feeding and stirring regimes

In anaerobic digestion plants (ADP) homogenization of the feed, the fermenter content and the microbial communities represents a precondition for effective and robust biogas production,but also a major energy consumer. For a 850 m3 agricultural AD-P equipped with eight sampling ports we investigated whether different feeding and stirring regimes enable a sufficient homogenization of the microbial communities using metaproteome and TRFLP analysis. Systematic comparison of the samples by scatter plots and students t-test revealed only a limited number of slightly changed metaproteins, taxonomies and biological processes, indicating no systematic differences between the microbial communities in center and rim as well as between top and bottom. However, comparison of the amount of shared identified metaproteins between the sample ports showed minor variation, which might be correlated with the applied stirring strategy. In sum, the applied stirring and feeding conditionswere sufficient to homogenize the microbial communities in AD-Ps largely.