Identity, abundance and ecophysiology of filamentous Chloroflexi species present in activated sludge treatment plants

• Published in: FEMS microbiology ecology 2007-03, Vol.59 (3), p.671-682
• Main Authors: Kragelund, Caroline, Levantesi, Caterina, Borger, Arjan, Thelen, Karin, Eikelboom, Dick, Tandoi, Valter, Kong, Yunhong, van der Waarde, Jaap, Krooneman, Janneke, Rossetti, Simona, Thomsen, Trine Rolighed, Nielsen, Per Halkjær
• Format: Article
• Language: English
• Subjects: Abundance; Activated sludge; Aerobic conditions; Aerobiosis; Bacteria; Bacterial Proteins - classification; Bacterial Proteins - metabolism; Bacterial Typing Techniques - methods; Bacteriology; Biodiversity; Biological and medical sciences; Carbohydrate Metabolism; Carbohydrates; Chitinase; Chloroflexi; Chloroflexi - classification; Chloroflexi - isolation & purification; Chloroflexi - physiology; Colony Count, Microbial; DNA Probes; Ecology; Ecophysiology; Enzymes - classification; Enzymes - metabolism; Filamentous bacteria; Filaments; Fundamental and applied biological sciences. Psychology; Genes, Bacterial - genetics; In Situ Hybridization, Fluorescence - methods; Industrial plants; Industrial Waste - analysis; Industrial wastes; Industrial wastewater; Industrial wastewater treatment; Microbiology; Miscellaneous; Molecular Sequence Data; New species; Phylogeny; Polysaccharides; Probes; Saccharides; Sewage - analysis; Sewage - microbiology; Sludge; Sludge treatment; Species Specificity; Waste Management; Wastewater treatment; Wastewater treatment plants; Water treatment
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2006.00251.x

Filamentous Chloroflexi species are often present in activated sludge wastewater treatment plants in relatively low numbers, although bulking incidences caused by Chloroflexi filaments have been observed. A new species-specific gene probe for FISH was designed and using phylum-, subdivision-, morphotype 1851- and species-specific gene probes, the abundance of Chloroflexi filaments were monitored in samples from 126 industrial wastewater treatment plants from five European countries. Chloroflexi filaments were present in 50% of the samples, although in low quantities. In most treatment plants the filaments could only be identified with phylum or subdivision probes, indicating the presence of great undescribed biodiversity. The ecophysiology of various Chloroflexi filaments was investigated by a suite of in situ methods. The experiments revealed that Chloroflexi constituted a specialized group of filamentous bacteria only active under aerobic conditions consuming primarily carbohydrates. Many exo-enzymes were excreted, e.g. chitinase, glucuronidase and galactosidase, suggesting growth on complex polysaccharides. The surface of Chloroflexi filaments appeared to be hydrophilic compared to other filaments present. These results are generally supported by physiological studies of two new isolates. Based on the results obtained in this study, the potential role of filamentous Chloroflexi species in activated sludge is discussed.