Spatial distribution of some microbial trophic groups in a plug-flow-type anaerobic bioreactor treating swine manure

摘要

Anaerobic digestion of swine manure is carried out by a consortium of microbial species,nincluding volatile fatty acid (VFA) producers, VFA-degraders and methanogens. The distribution ofnfive phylogenetic groups within a plug-flow-type anaerobic bioreactor consisting of eight seriallyconnectedntanks was examined through the sequential digestion of swine manure. Quantificationnwas carried out using reverse transcription real-time PCR (RT-Q-PCR) assays targeting the 16SnrRNA of Clostridium (cluster XIVa), Peptostreptococcus, Syntrophomonas, Methanosaeta, andnMethanosarcina spp. The VFA producers Peptostreptococcus spp. and Clostridium spp. werenfound predominantly in compartments where hydrolysis/acidogenesis took place. The spatialndistribution of the aceticlastic methanogens, Methanosaeta and Methanosarcina, within thenbioreactor was not correlated with methanogenic activity. In contrast the VFA-degrading genusnSyntrophomonas spp. was more abundant in compartments with elevated methanogenic activity.nMultivariate statistical analyses of the RT-Q-PCR data have provided new insights into ournunderstanding of how the various trophic groups were distributed within this bioreactor system.nWhile the distribution of clostridia, peptostreptococci and Syntrophomonas corresponded to theirnknown metabolic functions, aceticlastic methanogens were not apparently linked to thenmethanogenesis stage occurring in latter compartments, suggesting that hydrogenotrophicnmethanogens were the primary methane generators in this bioreactor. However, aceticlasticnmethanogens could be involved in compartments related to the hydrolysis/acidogenesis stage.