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Bacterial community compositions from 10 pulp- and paper-mill treatment systems were compared using both traditional and molecular techniques. 16S-RFLP (Random Fragment Length Polymorphisms) analysis was used to examine the genotypic profiles of the whole bacterial community of each treatment system. Although all the communities shared approximately 60% of their DNA band pattern, as determined by computer-assisted cluster analysis, each community displayed a unique profile that was stable over time under normal operating parameters. Reverse Sample Genome Probing (RSGP) and 16S-RFLP were used to compare the culturable bacterial communities of several geographically separated pulp-mill biotreatment system communities. There was little overlap in the composition of the culturable community between mills at the genus level. Furthermore, RSGP variation was almost as high within a mill as between mills. Partial sequences of the 16S rRNA genes from culturable isolates identified Bacillus spp., Pseudomonas spp., and Xanthobacter as some of the dominant species. Finally, several 16S rRNA genes from two whole community 16S RNA gene libraries were partially sequenced and identified as similar to unknown alpha-, beta-, and gamma-Proteobacteria, Ralstonia, Alcaligenes, Nitrospira, Firmicutes, and clones representing the new Holophaga/Acidobacterium phylum. These findings suggest that although these pulp- and paper-mill biotreatment communities perform similar functions, they are populated by unique mixtures of species.

The ability to differentiate functional and structural diversity of bacterial communities present in activated sludges adapted to elementally (ECF) and totally (TCF) chlorine-free bleaching effluents was evaluated. Community function was evaluated through substrate utilization patterns in BiologGN microplates, and taxonomic structure was evaluated by fluorescent in situ hybridization using probes targeting the Eubacteria; the alpha, beta, and gamma subclasses of the Proteobacteria; and gram-positive bacteria with high GC content. Over 6-week sampling periods, ECF-and TCF-adapted sludge bacterial communities presented reproducible substrate utilization patterns that through principal components (PCs) analysis, separated the ECF samples from the TCF samples. Application of the fluorescent in situ hybridization technique was complicated by the intense autofluorescence of the bleaching effluent sludge samples that interfered with detection of specific hybridization signals. The most notable difference in community structure detected using the chosen set of probes was the relatively greater proportion of cells of the alpha subclass in TCF sludge (27%) than in ECF sludge (6%). Nonspecific hybridization with beta and gamma probes was relatively high, but both sludges appeared to have similar proportions of cells of the beta (20-22%) and gamma (11-12%) subclasses. The two sludges presented relatively few gram-positive cells with high GC content (<0.2% of eubacterial counts). Differences in both metabolic potential and taxonomic structure of the microbial communities in the ECF- and TCF-activated sludges were detected. The kinetics of the development of these differences in treatment plants and their relationships with treatment efficiency and production process conditions should now be evaluated.