title: 16S ribosomal RNA tools identify an unexpected predominance of Paenibacillus-like bacteria in an industrial activated sludge system suffering from poor biosolids separation.
abstract: Molecular biology tools targeting 16S ribosomal RNA (16S rRNA) were used to identify a predominant bacterial population in a full-scale dairy wastewater activated sludge system suffering from poor biosolids separation. Gram and acridine orange staining indicated that viable, Gram-positive microorganisms were present in samples removed from the influent waste stream and represented approximately 50% of total cell counts in samples removed from the mixed liquor. Subsequently, the "full-cycle 16S rRNA approach" showed that phylogenetic relatives of Paenibacillus spp., a low guanine-plus-cytosine percent DNA-content, Gram-positive microorganism, represented up to 30% of total 4,6-diamidino-2-phenylindole (DAPI)-stained cell counts in samples of mixed liquor. Although fluorescent in situ hybridizations with 16S rRNA-targeted oligonucleotide hybridization probes identified Paenibacillus-like spp. in samples removed from the influent waste stream, their abundance was less than 10% of total stained cell counts. Results of this study suggest that Paenibacillus-like spp. were present in low abundance in the influent waste stream, increased in relative abundance within the treatment system, and should be examined further as a candidate bacterial population responsible for poor biosolids separation. This study demonstrates that the full-cycle 16S rRNA approach can be used to identify candidate bacterial populations that may be responsible for operational upsets in full-scale activated sludge systems without prior information from cultivation or microscopic analyses.
authors.affiliation: Department of Civil and Environmental Engineering, University of Cincinnati, Ohio 45221-0071, USA.
authors.forename: Joyce M
authors.initials: JM
authors.lastname: Simpson
authors.forename: Peter G
authors.initials: PG
authors.lastname: Stroot
authors.forename: Steve
authors.initials: S
authors.lastname: Gelman
authors.forename: Inan
authors.initials: I
authors.lastname: Beydilli
authors.forename: Sandra
authors.initials: S
authors.lastname: Dudley
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Oerther
mesh_terms: D001406:Bacillaceae / Q000302:isolation & purification*; D003611:Dairy Products / Q000382:microbiology; D004868:Equipment Failure; D019649:Food Industry / Q000379:methods; D007220:Industrial Waste; D008954:Models, Biological; D010802:Phylogeny; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis*; D014462:Ultrafiltration / Q000379:methods; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D014871:Water Microbiology
chemical_list: D007220:Industrial Waste; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S