title: Quantification of Hyphomicrobium populations in activated sludge from an industrial wastewater treatment system as determined by 16S rRNA analysis.
abstract: The bacterial community structure of the activated sludge from a 25 million-gal-per-day industrial wastewater treatment plant was investigated using rRNA analysis. 16S ribosomal DNA (rDNA) libraries were created from three sludge samples taken on different dates. Partial rRNA gene sequences were obtained for 46 rDNA clones, and nearly complete 16S rRNA sequences were obtained for 18 clones. Seventeen of these clones were members of the beta subdivision, and their sequences showed high homology to sequences of known bacterial species as well as published 16S rDNA sequences from other activated sludge sources. Sixteen clones belonged to the alpha subdivision, 7 of which showed similarity to Hyphomicrobium species. This cluster was chosen for further studies due to earlier work on Hyphomicrobium sp. strain M3 isolated from this treatment plant. A nearly full-length 16S rDNA sequence was obtained from Hyphomicrobium sp. strain M3. Phylogenetic analysis revealed that Hyphomicrobium sp. strain M3 was 99% similar to Hyphomicrobium denitrificans DSM 1869(T) in Hyphomicrobium cluster II. Three of the cloned sequences from the activated sludge samples also grouped with those of Hyphomicrobium cluster II, with a 96% sequence similarity to that of Hyphomicrobium sp. strain M3. The other four cloned sequences from the activated sludge sample were more closely related to those of the Hyphomicrobium cluster I organisms (95 to 97% similarity). Whole-cell fluorescence hybridization of microorganisms in the activated sludge with genus-specific Hyphomicrobium probe S-G-Hypho-1241-a-A-19 enhanced the visualization of Hyphomicrobium and revealed that Hyphomicrobium appears to be abundant both on the outside of flocs and within the floc structure. Dot blot hybridization of activated sludge samples from 1995 with probes designed for Hyphomicrobium cluster I and Hyphomicrobium cluster II indicated that Hyphomicrobium cluster II-positive 16S rRNA dominated over Hyphomicrobium cluster I-positive 16S rRNA by 3- to 12-fold. Hyphomicrobium 16S rRNA comprised approximately 5% of the 16S rRNA in the activated sludge.
authors.affiliation: Center for Environmental Biotechnology, The University of Tennessee, Knoxville, Tennessee 37996, USA. alayton@utk.edu
authors.forename: A C
authors.initials: AC
authors.lastname: Layton
authors.forename: P N
authors.initials: PN
authors.lastname: Karanth
authors.forename: C A
authors.initials: CA
authors.lastname: Lajoie
authors.forename: A J
authors.initials: AJ
authors.lastname: Meyers
authors.forename: I R
authors.initials: IR
authors.lastname: Gregory
authors.forename: R D
authors.initials: RD
authors.lastname: Stapleton
authors.forename: D E
authors.initials: DE
authors.lastname: Taylor
authors.forename: G S
authors.initials: GS
authors.lastname: Sayler
mesh_terms: D003001:Cloning, Molecular; D017753:Ecosystem; D020582:Hyphomicrobium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D017404:In Situ Hybridization, Fluorescence; D007220:Industrial Waste; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000032:analysis*; D012336:RNA, Ribosomal, 16S / Q000032:analysis*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid
chemical_list: D007220:Industrial Waste; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage