Fig. 1
Taxonomic distribution and NMDS (Bray–Curtis dissimilarities in community structures) clustering analysis of a, c bacteria and b, d archaea for the 20 monitored mesophilic AD reactors (10 AD units) during the 1-year monitoring survey. For each reactor the 12 bars represent the monthly progress of the taxonomic distribution over the 1-year survey (a, b). In the case of the units 3, 4, 5, and 7 more than one reactor was analysed (see Table 1 for details). The AD categories refer to: “farm”—farm reactors fed mainly with agricultural residues, “bio-waste”—reactors treating bio-waste (a mixture of agricultural residues including manure and municipal and industrial bio-waste), “MSW”—a biogas unit treating sorted municipal solid waste and green waste and “WWTP-ADs”—anaerobic digesters of WWTPs (fed with sewage-activated sludge). An approximate ratio of animal manure to MSW in the reactor feed for the different reactors is shown above graph a. For NMDS graphs stress value and R2 for the two configurations equalled 0.2, 0.9 and ANOSIM R global was equal to 0.9 and 0.8, with p < 0.001, for bacteria and archaea, respectively