scholarly journals Monitoring the conjugal transfer of plasmid RP4 in activated sludge and in situ identification of the transconjugants

1999 ◽  
Vol 174 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Otto Geisenberger ◽  
Aldo Ammendola ◽  
Bjarke B Christensen ◽  
S�ren Molin ◽  
Karl-Heinz Schleifer ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Conjugal Transfer

scholarly journals Time-series genome-centric analysis unveils bacterial response to operational disturbance in activated sludge

2019 ◽  
Author(s):  
María Victoria Pérez ◽  
Leandro D. Guerrero ◽  
Esteban Orellana ◽  
Eva L. Figuerola ◽  
Leonardo Erijman
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Microbial Communities ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Operating Conditions ◽  
The Face

ABSTRACTUnderstanding ecosystem response to disturbances and identifying the most critical traits for the maintenance of ecosystem functioning are important goals for microbial community ecology. In this study, we used 16S rRNA amplicon sequencing and metagenomics to investigate the assembly of bacterial populations in a full-scale municipal activated sludge wastewater treatment plant over a period of three years, including a period of nine month of disturbance, characterized by short-term plant shutdowns. Following the reconstruction of 173 metagenome-assembled genomes, we assessed the functional potential, the number of rRNA gene operons and thein situgrowth rate of microorganisms present throughout the time series. Operational disturbances caused a significant decrease in bacteria with a single copy of the ribosomal RNA (rrn) operon. Despite only moderate differences in resource availability, replication rates were distributed uniformly throughout time, with no differences between disturbed and stable periods. We suggest that the length of the growth lag phase, rather than the growth rate, as the primary driver of selection under disturbed conditions. Thus, the system could maintain its function in the face of disturbance by recruiting bacteria with the capacity to rapidly resume growth under unsteady operating conditions.IMPORTANCEIn this work we investigated the response of microbial communities to disturbances in a full-scale activated sludge wastewater treatment plant over a time-scale that included periods of stability and disturbance. We performed a genome-wide analysis, which allowed us the direct estimation of specific cellular traits, including the rRNA operon copy number and the in situ growth rate of bacteria. This work builds upon recent efforts to incorporate growth efficiency for the understanding of the physiological and ecological processes shaping microbial communities in nature. We found evidence that would suggest that activated sludge could maintain its function in the face of disturbance by recruiting bacteria with the capacity to rapidly resume growth under unsteady operating conditions. This paper provides relevant insights into wastewater treatment process, and may also reveal a key role for growth traits in the adaptive response of bacteria to unsteady environmental conditions.

In situ detection of cell surface hydrophobicity of probe-defined bacteria in activated sludge

2001 ◽  
Vol 43 (6) ◽  
pp. 97-103 ◽  
Author(s):  
J. L. Nielsen ◽  
L. H. Mikkelsen ◽  
P. H. Nielsen
Keyword(s):  
Activated Sludge ◽  
Surface Properties ◽  
Treatment Plant ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Substrate Uptake ◽  
Filamentous Bacteria ◽  
In Situ Conditions ◽  
Bacterial Surfaces

The surface hydrophobicity of different types of bacteria in activated sludge were investigated under in situ conditions by following the adhesion of fluorescent microspheres with defined surface properties to bacterial surfaces (the MAC-method). This technique was combined with identification of the bacteria with fluorescence in situ hybridization with rRNA-targeted oligonucleotides (FISH) and could thus be used for characterization of surface properties of probe-defined bacteria directly in a complex system without prior enrichment or isolation. This MAC-FISH technique could be used for single bacteria as well as filamentous bacteria. In the investigated activated sludge from an industrial wastewater treatment plant, two types of filamentous bacteria dominated. One morphotype consistently attracted only very few hydrophobic microspheres, indicating that the thin sheath of exopolymers around the cells had a hydrophilic surface. Use of a hierarchical set of gene probes revealed that these filaments were sulphide oxidising Thiothrix spp. The other predominating filamentous morphotype had a thick, very hydrophobic exopolymeric sheath. This filamentous bacterium was found to belong to the alpha-Proteobacteria. The relevance of the significant differences in surface hydrophobicity for the two morphotypes in respect to substrate uptake and floc formation is discussed.

Microbial quantification in activated sludge: the hits and misses

2003 ◽  
Vol 48 (3) ◽  
pp. 121-126 ◽  
Author(s):  
S.J. Hall ◽  
J. Keller ◽  
L.L. Blackall
Keyword(s):  
Activated Sludge ◽  
Molecular Genetic ◽  
In Situ Hybridisation ◽  
Biological Nutrient Removal ◽  
Physical Parameters ◽  
Fluorescence In Situ Hybridisation ◽  
Batch Tests ◽  
Polymerase Chain ◽  
Key Microorganisms

Since the implementation of the activated sludge process for treating wastewater, there has been a reliance on chemical and physical parameters to monitor the system. However, in biological nutrient removal (BNR) processes, the microorganisms responsible for some of the transformations should be used to monitor the processes with the overall goal to achieve better treatment performance. The development of in situ identification and rapid quantification techniques for key microorganisms involved in BNR are required to achieve this goal. This study explored the quantification of Nitrospira, a key organism in the oxidation of nitrite to nitrate in BNR. Two molecular genetic microbial quantification techniques were evaluated: real-time polymerase chain reaction (PCR) and fluorescence in situ hybridisation (FISH) followed by digital image analysis. A correlation between the Nitrospira quantitative data and the nitrate production rate, determined in batch tests, was attempted. The disadvantages and advantages of both methods will be discussed.

Application of oligonucleotide probes for the detection of Thiothrix spp. in activated sludge plants treating paper and board mill wastes

2002 ◽  
Vol 46 (1-2) ◽  
pp. 559-564 ◽  
Author(s):  
S.B. Kim ◽  
M. Goodfellow ◽  
J. Kelly ◽  
G.S. Saddler ◽  
A.C. Ward
Keyword(s):  
Activated Sludge ◽  
Bacterial Population ◽  
Oligonucleotide Probe ◽  
In Situ Hybridisation ◽  
Filamentous Bacteria ◽  
Phylogenetic Groups ◽  
Investigation Period ◽  
Mixed Populations ◽  
Conventional Microscopy

Filamentous bacteria belonging to the genus Thiothrix were detected in activated sludge samples using the fluorescent in situ hybridisation (FISH) technique. A 16S rRNA-targeted oligonucleotide probe was developed for the detection of members of the T. fructosivorans group, and the performance of probe TNI for the detection of Thiothrix nivea group was enhanced by using an unlabeled competitor. A set of 5 probes covering all phylogenetic groups of Thiothrix were used to examine samples taken from selected activated sludge plants treating paper and board mill wastes. Members of the T. eikelboomii group formed the predominant filamentous bacterial population in plants experiencing poor sludge settleability, whereas members of the T. nivea group were commonly found but not dominantly in the remaining plants. Members of the T. fructosivorans group were not detected at any significant level in any of the samples. The distribution of the main Thiothrix types remained unchanged throughout the investigation period. It was evident that mixed populations of Thiothrix spp. were present in all activated sludge samples investigated, the observed differences were in the relative abundance of the various groups. These findings were supported by the results obtained using conventional microscopy.

Combining fluorescent in situ hybridization (fish) with cultivation and mathematical modeling to study population structure and function of ammonia-oxidizing bacteria in activated sludge

1998 ◽  
Vol 37 (4-5) ◽  
pp. 441-449 ◽  
Author(s):  
Michael Wagner ◽  
Daniel R. Noguera ◽  
Stefan Juretschko ◽  
Gabriele Rath ◽  
Hans-Peter Koops ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
In Situ Hybridization ◽  
Activated Sludge ◽  
Heterotrophic Bacteria ◽  
Sewage Treatment Plant ◽  
Laser Scanning Microscopy ◽  
Industrial Plant ◽  
Ammonia Oxidizing Bacteria ◽  
Ammonia Oxidizers

16S rRNA-targeted oligonucleotide probes for phylogenetically defined groups of autotrophic ammonia-oxidizing bacteria were used for analyzing the natural diversity of nitrifiers in an industrial sewage treatment plant receiving sewage with high ammonia concentrations. In this facility discontinuous aeration is used to allow for complete nitrification and denitrification. In situ hybridization revealed a yet undescribed diversity of ammonia oxidizers occurring in the plant. Surprisingly, the majority of the ammonia oxidizers were detected with probe combinations which indicate a close affiliation of these cells with Nitrosococcus mobilis. In addition, low numbers of ammonia-oxidizers related to the Nitrosomonas europaea - Nitrosomonas eutropha cluster were present. Interestingly, we also observed hybridization patterns which suggested the occurrence of a novel population of ammonia oxidizers. Confocal laser scanning microscopy revealed that all specifically stained ammonia oxidizers were clustered in microcolonies formed by rod-shaped bacteria. Combination of FISH and mathematical modeling was used to investigate diffusion limitation of ammonia and O2 within these aggregates. Model simulations suggest that mass transfer limitations inside the clusters are not as significant as the substrate limitations due to the activity of surrounding heterotrophic bacteria. To learn more about the ammonia-oxidizers of the industrial plant, we enriched and isolated ammonia-oxidizing bacteria from the activated sludge by combining classical cultivation techniques and FISH. Monitoring the isolates with the nested probe set allowed us to specifically identify those ammonia oxidizers which were found in situ to be numerically dominant. The phylogenetic relationship of these isolates determined by comparative 16S rDNA sequence analysis confirmed the affiliation suggested by FISH.

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