Filamentous Scum Bacteria in Activated Sludge Plants: Detection and Identification Quality by Conventional Activated Sludge Microscopy versus Fluorescence In Situ Hybridization

Abstract

Detection of filamentous bacteria morphotypes involved in scum formation in activated sludge wastewater treatment plants by conventional sludge microscopy is often doomed to fail because of morphological and taxonomical variations. The aim of this study is to compare detection, identification, and quantification quality of filamentous ''scum bacteria'' found by conventional activated sludge microscopy and fluorescence in situ hybridization (FISH). In the case of filamentous Microthrix parvicella and Eikelboom morphotypes 1863 and 1851, conventional activated sludge microscopy and FISH results correspond well. In contrast, conventional activated sludge microscopy overlooks nocardioform actinomycete and type 1863 single cells. On the other hand, FISH underestimates filamentous nocardioform actinomycetes and morphotypes 0041/0675 or 0092 because of insufficient cell wall permeability or because of their taxonomic variability, with a resulting inadequacy of previously published probes. Nostocoida limicola morphotype results are still inconclusive because of low bacteria numbers being available in situ and the enormous taxonomic variability within this group. Water Environ. Res., 79, 2274Res., 79, (2007.

A review of practical tools for rapid monitoring of membrane bioreactors

“…With the advent of molecular methods for identification of microbes, the inexact nature of morphological typing became has become evident (Müller et al, 2007). For example some filamentous organisms are able to revert to a unicellular form at some stages of their lifecycle (Ramothokang et al, 2006).…”

A systematic insight into a single-stage deammonification process operated in granular sludge reactor with high-loaded reject-water: characterization and quantification of microbiological community

“…A combination of forward primer specific for Planctomycetes PLA40F: 5′‐GGA TTA GGC ATG CAA GTC‐3′ and universal bacterial reverse primer 518R: 5′‐ATT ACC GCG GCT GCT G‐3′ were used to amplify the partial 16S rRNA gene of Planctomycetes (Müller et al . ()). A 40‐nucleotide GC‐clamp was added to 518R at 5′ end to improve the detection of sequence variation by DGGE (Muyzer et al .…”

“…Twenty different microscopic fields were randomly selected for the homogenized granules, and positive FISH signals were quantified using class indexes according to the study by Müller et al . (). After the cryosection of the granule, five sections were analysed and mean values were calculated from these five sections.…”

“…Hybridized sample were analysed using an acquisition system LSM 510 META laser scanning microscope (Zeiss, LSM510 META) controlled by confocal software v3.2 (Zeiss, Göttingen, Germany). Twenty different microscopic fields were randomly selected for the homogenized granules, and positive FISH signals were quantified using class indexes according to the study by Müller et al (2007).…”

Analysis and in situ characterization of activated sludge communities capable of benzotriazole biodegradation

“…Microscopic analyses were performed with an Axioplan epifluorescence microscope (Carl Zeiss, Jena, Germany) to detect hybridized and DAPI stained cells. Positive hybridized cells were quantified using class indexes as described elsewhere [47], with category 0, denoting the lack of specific signals and category 5 the excessive occurrence thereof.…”