It has become evident that aggregation or biofilm formation is an important survival mechanism for bacteria in almost any environment. In this review

Filamentous Chloroflexi species are often present in activated sludge wastewater treatment plants in relatively low numbers, although bulking incidenc

The identity and ecophysiology of a group of uncultured protein-hydrolyzing epiphytic rods attached to filamentous bacteria in activated sludge from nutrient removal plants were investigated by using the full-cycle rRNA approach combined with microautoradiography and histochemical staining. The epiphytic group consists of three closely related clusters, each containing 11 to 16 clones. The closest related cultured isolate is the type strainHaliscomenobacter hydrossis(ATCC 27775) (<87% similarity) in the familySaprospiraceaeof the phylumBacteroidetes. Oligonucleotide probes at different hierarchical levels were designed for each cluster and used for ecophysiological studies. All three clusters behaved similarly in their physiology and were specialized in protein hydrolysis and used amino acids as energy and carbon sources. They were not involved in denitrification. No storage of polyphosphate and polyhydroxyalkanoates was found. They all colonized probe-defined filamentous bacteria belonging to the phylaChloroflexi,Proteobacteria, and candidate phylum TM7, with the exception of cluster 1, which did not colonize TM7 filaments. The three epiphytic clusters were all widespread in domestic and industrial wastewater treatment plants with or without biological phosphorus removal, constituting, in total, up to 9% of the bacterial biovolume. A new genus, “CandidatusEpiflobacter,” is proposed for this epiphytic group in activated-sludge treatment plants, where it presumably plays an important role in protein degradation.

The abundance of potential denitrifiers in full-scale wastewater treatment plants with biological nitrogen and phosphorus removal was investigated by

Anaerobic methane oxidation was investigated in 6-m-long cores of marine sediment from Aarhus Bay, Denmark. Measured concentration profiles for methane and sulfate, as well as in situ rates determined with isotope tracers, indicated that there was a narrow zone of anaerobic methane oxidation about 150 cm below the sediment surface. Methane could account for 52% of the electron donor requirement for the peak sulfate reduction rate detected in the sulfate-methane transition zone. Molecular signatures of organisms present in the transition zone were detected by using selective PCR primers for sulfate-reducing bacteria and for Archaea . One primer pair amplified the dissimilatory sulfite reductase (DSR) gene of sulfate-reducing bacteria, whereas another primer (ANME) was designed to amplify archaeal sequences found in a recent study of sediments from the Eel River Basin, as these bacteria have been suggested to be anaerobic methane oxidizers (K. U. Hinrichs, J. M. Hayes, S. P. Sylva, P. G. Brewer, and E. F. DeLong, Nature 398:802–805, 1999). Amplification with the primer pairs produced more amplificate of both target genes with samples from the sulfate-methane transition zone than with samples from the surrounding sediment. Phylogenetic analysis of the DSR gene sequences retrieved from the transition zone revealed that they all belonged to a novel deeply branching lineage of diverse DSR gene sequences not related to any previously described DSR gene sequence. In contrast, DSR gene sequences found in the top sediment were related to environmental sequences from other estuarine sediments and to sequences of members of the genera Desulfonema , Desulfococcus , and Desulfosarcina . Phylogenetic analysis of 16S rRNA sequences obtained with the primers targeting the archaeal group of possible anaerobic methane oxidizers revealed two clusters of ANME sequences, both of which were affiliated with sequences from the Eel River Basin.

The diversity of sulfate-reducing bacteria (SRB) inhabiting the extreme hypersaline sediment (270 g L−1 NaCl) of the northern arm of Great Salt Lake w