QUALITATIVE AND QUANTITATIVE RESPONSE OF BACTERIAL AND ARCHAEAL COMMUNITIES TO SUBSTRATE-LIMITED CONDITIONS IN A TWO-STAGE ANAEROBIC PROCESS TREATING SWINE SLURRY AND MARKET BIO-WASTE

The dynamics of bacterial and archaeal communities, associated with process performance data, were investigated in a two-stage anaerobic digestion process treating swine slurry and market bio-waste and operating for 60 days under thermophilic conditions. Qualitative and quantitative responses of microbial community were monitored before and after a 15-days starvation period by Denaturing Gradient Gel Electrophoresis (DGGE) and real-time PCR techniques, respectively. The DGGE 16S rRNA gene analysis showed after the starvation period a significant shift of microbial community in the acidogenic reactor compared to a substantial stability of the archaeal community in the methanogenic reactor. The quantitative real-time analyses targeting the main phylogenetic and trophic microbial groups showed only limited changes in the number of bacterial and archaeal cells before and after the starvation period in both the acidogenic and methanogenic processes. Taken together, microbial results showed good agreement with process data indicating a good performance of the anaerobic digestion process to the stress induced by starvation.