Determination of the microbial diversity of anaerobic-aerobic activated sludge by a novel molecular biological technique

Liu, Wen-Tso; Marsh, Terence L.; Forney, Larry J.

doi:10.1016/s0273-1223(98)00141-3

Cited by 25 publications

(1 citation statement)

References 17 publications

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“…Whereas bacterial community dynamics at reactor scale (Liu et al, 1998) can be assessed by terminal-restriction fragment length polymorphism (T-RFLP) analysis, biofilm architecture and microbial arrangements can be examined by confocal laser scanning microscopy (CLSM) combined with fluorescence in situ hybridization (FISH) (Wagner et al, 1994; Wuertz et al, 2004; Nielsen et al, 2009; Neu et al, 2010). Localization of bacterial populations along dissolved oxygen (DO) gradients in granules has been investigated with the latter methods (Tsuneda et al, 2003; Kishida et al, 2006; Lemaire et al, 2008a; Yilmaz et al, 2008; Gao et al, 2010; Filali et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Assessment of bacterial and structural dynamics in aerobic granular biofilms

Weissbrodt¹,

Neu²,

Kuhlicke³

et al. 2013

Front. Microbiol.

128

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Aerobic granular sludge (AGS) is based on self-granulated flocs forming mobile biofilms with a gel-like consistence. Bacterial and structural dynamics from flocs to granules were followed in anaerobic-aerobic sequencing batch reactors (SBR) fed with synthetic wastewater, namely a bubble column (BC-SBR) operated under wash-out conditions for fast granulation, and two stirred-tank enrichments of Accumulibacter (PAO-SBR) and Competibacter (GAO-SBR) operated at steady-state. In the BC-SBR, granules formed within 2 weeks by swelling of Zoogloea colonies around flocs, developing subsequently smooth zoogloeal biofilms. However, Zoogloea predominance (37–79%) led to deteriorated nutrient removal during the first months of reactor operation. Upon maturation, improved nitrification (80–100%), nitrogen removal (43–83%), and high but unstable dephosphatation (75–100%) were obtained. Proliferation of dense clusters of nitrifiers, Accumulibacter, and Competibacter from granule cores outwards resulted in heterogeneous bioaggregates, inside which only low abundance Zoogloea (<5%) were detected in biofilm interstices. The presence of different extracellular glycoconjugates detected by fluorescence lectin-binding analysis showed the complex nature of the intracellular matrix of these granules. In the PAO-SBR, granulation occurred within two months with abundant and active Accumulibacter populations (56 ± 10%) that were selected under full anaerobic uptake of volatile fatty acids and that aggregated as dense clusters within heterogeneous granules. Flocs self-granulated in the GAO-SBR after 480 days during a period of over-aeration caused by biofilm growth on the oxygen sensor. Granules were dominated by heterogeneous clusters of Competibacter (37 ± 11%). Zoogloea were never abundant in biomass of both PAO- and GAO-SBRs. This study showed that Zoogloea, Accumulibacter, and Competibacter affiliates can form granules, and that the granulation mechanisms rely on the dominant population involved.

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Section: Introductionmentioning

confidence: 99%

Assessment of bacterial and structural dynamics in aerobic granular biofilms

Weissbrodt¹,

Neu²,

Kuhlicke³

et al. 2013

Front. Microbiol.

128

View full text Add to dashboard Cite

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Multilevel correlations in the biological phosphorus removal process: From bacterial enrichment to conductivity‐based metabolic batch tests and polyphosphatase assays

Weissbrodt

Maillard

Brovelli

et al. 2014

Biotech & Bioengineering

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Enhanced biological phosphorus removal (EBPR) from wastewater relies on the preferential selection of active polyphosphate-accumulating organisms (PAO) in the underlying bacterial community continuum. Efficient management of the bacterial resource requires understanding of population dynamics as well as availability of bioanalytical methods for rapid and regular assessment of relative abundances of active PAOs and their glycogen-accumulating competitors (GAO). A systems approach was adopted here toward the investigation of multilevel correlations from the EBPR bioprocess to the bacterial community, metabolic, and enzymatic levels. Two anaerobic-aerobic sequencing-batch reactors were operated to enrich activated sludge in PAOs and GAOs affiliating with "Candidati Accumulibacter and Competibacter phosphates", respectively. Bacterial selection was optimized by dynamic control of the organic loading rate and the anaerobic contact time. The distinct core bacteriomes mainly comprised populations related to the classes Betaproteobacteria, Cytophagia, and Chloroflexi in the PAO enrichment and of Gammaproteobacteria, Alphaproteobacteria, Acidobacteria, and Sphingobacteria in the GAO enrichment. An anaerobic metabolic batch test based on electrical conductivity evolution and a polyphosphatase enzymatic assay were developed for rapid and low-cost assessment of the active PAO fraction and dephosphatation potential of activated sludge. Linear correlations were obtained between the PAO fraction, biomass specific rate of conductivity increase under anaerobic conditions, and polyphosphate-hydrolyzing activity of PAO/GAO mixtures. The correlations between PAO/GAO ratios, metabolic activities, and conductivity profiles were confirmed by simulations with a mathematical model developed in the aqueous geochemistry software PHREEQC.

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