Dynamics of Clostridium consortia in mesophilic lab-scale anaerobic digesters fed with agricultural biomass and cattle manure

Introduction The biological process of anaerobic digestion cannot totally prevent the recontamination and regrowth of pathogenic bacteria. The presence of some clostridial species could also be controversial for the hard-cheese manufacturing industries, which also utilize biogas plants for energy recovery. Indeed, some species of Clostridium (i.e., C. tyrobutyricum, C. butyricum, C. sporogenes) are known to be responsible for the blowing defects of hard cheeses. Since Clostridium spp. are known to be among the main players during the hydrolytic and acidogenic phases of anaerobic digestion, it is important to assess whether the presence of some clostridial species in the digestate of biogas plants could be problematic in terms of biological risk for both agronomic purposes and food industry processes. The aim of this study was to investigate the effect of the anaerobic digestion process on the Clostridium consortia distribution.