Examination of two years of community dynamics in an anaerobic bioreactor using fluorescence polymerase chain reaction (PCR) single-strand conformation polymorphism analysis

The structures of the bacterial and archaeal communities in an anaerobic di gester were monitored over a 2 year period. The study was performed on a fl uidized bed reactor fed with vinasse. The objective was to characterize the population dynamics over a long time period under constant environmental p arameters. Total bacterial and archaeal populations were measured independe ntly by fluorescence-based polymerase chain reaction (PCR) single-strand co nformation polymorphism (SSCP) analysis using an automated DNA sequencer. W ith the current level of accuracy, the technique was able to monitor 45 bac terial and seven archaeal 16S rDNA molecules. The community dynamics were c ompared with molecular inventories of the microbial community based on 16S rDNA sequences done at the beginning of the study. The six archaeal and the 22 most frequent bacterial operational taxonomic units (OTUs) identified w ere associated with their SSCP peak counterparts. Overall, the data indicat ed that, throughout the period of the study, rapid significant shifts in th e species composition of the bacterial community occurred, whereas the arch aeal community remained relatively stable.