DETERMINATION OF THE MICROBIAL DIVERSITY OF ANAEROBIC-AEROBIC ACTIVATED-SLUDGE BY A NOVEL MOLECULAR BIOLOGICAL TECHNIQUE

Sequential anaerobic-aerobic batch reactors were maintained on acetate /peptone and two different P/total organic carbon ratios that select f or microbial communities enriched for either glycogen-accumulating org anisms (GAO) or polyphosphate-accumulating organism (PAG): The communi ty profiles of the eubacterial population and gram-positive high G-C b acteria (HGC) were characterized and compared by determining the termi nal restriction fragment length polymorphisms (T-RFLP) of 16S rDNA. Th e HhaI+RsaI digested 5' T-RFLP patterns of the eubacterial 16S rDNA am plified from the GAO-and PAO-enriched communities were made up with 12 and 14 rank-abundant fragments (i.e., ribotypes), respectively. Among these ribotypes detected in the GAG-enriched community, only seven we re found in the PAO-enriched community. The HGC group could only accou nt for no more than 6% and 17% of the eubacterial 16S rDNA amplified f rom the GAO-and PAO-enriched communities, respectively. Within the HGC community, at least 16 and 10 rank-abundant ribotypes were observed i n the MspI digested T-RFLP patterns of GAO-and PAO-enriched communitie s, respectively. Among those HGC ribotypes observed in both communitie s, only five were in common. These indicate that the enrichment proces ses leading io;the establishment ol. GAO-and FAG-specific communities caused the dramatic difference and complexity in the microbial populat ion. (C) 1998 IAWQ. Published by Elsevier Science Ltd.