scholarly journals Genomic and Metabolic Insights into Two Novel Thiothrix Species from Enhanced Biological Phosphorus Removal Systems

2020 ◽  
Vol 8 (12) ◽  
pp. 2030
Author(s):  
Andrey V. Mardanov ◽  
Eugeny V. Gruzdev ◽  
Dmitry D. Smolyakov ◽  
Tatyana S. Rudenko ◽  
Alexey V. Beletsky ◽  
...  

Two metagenome-assembled genomes (MAGs), obtained from laboratory-scale enhanced biological phosphorus removal bioreactors, were analyzed. The values of 16S rRNA gene sequence identity, average nucleotide identity, and average amino acid identity indicated that these genomes, designated as RT and SSD2, represented two novel species within the genus Thiothrix, ‘Candidatus Thiothrix moscowensis’ and ‘Candidatus Thiothrix singaporensis’. A complete set of genes for the tricarboxylic acid cycle and electron transport chain indicates a respiratory type of metabolism. A notable feature of RT and SSD2, as well as other Thiothrix species, is the presence of a flavin adenine dinucleotide (FAD)-dependent malate:quinone oxidoreductase instead of nicotinamide adenine dinucleotide (NAD)-dependent malate dehydrogenase. Both MAGs contained genes for CO2 assimilation through the Calvin–Benson–Bassam cycle; sulfide oxidation (sqr, fccAB), sulfur oxidation (rDsr complex), direct (soeABC) and indirect (aprBA, sat) sulfite oxidation, and the branched Sox pathway (SoxAXBYZ) of thiosulfate oxidation to sulfur and sulfate. All these features indicate a chemoorganoheterotrophic, chemolithoautotrophic, and chemolithoheterotrophic lifestyle. Both MAGs comprise genes for nitrate reductase and NO-reductase, while SSD2 also contains genes for nitrite reductase. The presence of polyphosphate kinase and exopolyphosphatase suggests that RT and SSD2 could accumulate and degrade polyhosphates during the oxic-anoxic growth cycle in the bioreactors, such as typical phosphate-accumulating microorganisms.

Microbiology ◽  
2011 ◽  
Vol 157 (8) ◽  
pp. 2287-2296 ◽  
Author(s):  
Jeong Myeong Kim ◽  
Hyo Jung Lee ◽  
Dae Sung Lee ◽  
Kangseok Lee ◽  
Che Ok Jeon

The presence of glycogen-accumulating organisms (GAO) has been hypothesized to be a cause of deterioration in enhanced biological phosphorus removal (EBPR) processes due to their abilities to out-compete polyphosphate-accumulating organisms (PAO). Based on 16S rRNA gene sequences, new members of uncultured gammaproteobacterial GAO (GB) were identified from sludge samples of a lab-scale sequencing batch reactor used for EBPR. The new GB formed a phylogenetic lineage (GB8) clearly distinct from the previously reported seven GB subgroups. Because the new GB8 members were not targeted by the known fluorescence in situ hybridization (FISH) oligonucleotide probes, a GB8-specific FISH probe (GB429) and a new FISH probe (GB742) targeting all eight GB subgroups were designed, and the phenotypic properties of the new GB8 members were investigated. FISH and microautoradiography approaches showed that GB429-targeted cells (GB8) were large coccobacilli (2–4 µm in size) with the ability to take up acetate under anaerobic conditions, but unable to accumulate polyphosphate under the subsequent aerobic conditions, consistent with in situ phenotypes of GB. FISH analyses on several sludge samples showed that members of GB8 were commonly detected as the majority of GB in lab- and full-scale EBPR processes. In conclusion, this study showed that members of GB8 could be a subgroup of GB with an important role in EBPR deterioration. Designs of FISH probes which hybridize with broader GB subgroups at different hierarchical levels will contribute to studies of the distributions and ecophysiologies of GB in lab- or full-scale EBPR plants.


2021 ◽  
Author(s):  
Guanglei Qiu ◽  
Yingyu Law ◽  
Rogelio Zuniga-Montanez ◽  
Yang Lu ◽  
Samarpita Roy ◽  
...  

AbstractRecent research has shown enhanced biological phosphorus removal (EBPR) from municipal wastewater at warmer temperatures around 30°C to be stable in both laboratory-scale reactors and full-scale treatment plants. In the context of a changing climate, the feasibility of EBPR at even higher temperatures is of interest. We operated two lab-scale EBPR sequencing batch reactors with alternating anaerobic and aerobic phases for over 300 days at 30°C and 35°C, respectively, and followed the dynamics of the communities of phosphorus accumulating organisms (PAOs) and competing glycogen accumulating organisms (GAOs) using a combination of 16S rRNA gene metabarcoding, quantitative PCR and fluorescent in-situ hybridization analyses. Stable and nearly complete P removal was achieved at 30°C; similarly, long term P removal was stable at 35°C with effluent PO43−-P concentrations < 0.5 mg/L on half of all monitored days. Diverse and abundant Ca. Accumulibacter amplicon sequence variants were closely related to those found in temperate environments, suggesting that EBPR at this temperature does not require a highly specialized PAO community. The slow-feeding strategy used effectively limited the carbon uptake rates of GAOs, allowing PAOs to outcompete GAOs at both temperatures. Candidatus Competibacter was the main GAO, along with cluster III Defluviicoccus members. These organisms withstood the slow-feeding regime, suggesting that their bioenergetic characteristics of carbon uptake differ from those of their tetrad-forming relatives. This specific lineage of GAOs warrants further study to establish how complete P removal can be maintained. Comparative cycle studies at two temperatures for each reactor revealed higher activity of Ca. Accumulibacter when the temperature was increased from 30°C to 35°C, suggesting that the stress was a result of the higher carbon (and/or P) metabolic rates of PAOs and GAOs, the resultant carbon deficiency, and additional community competition. An increase in the TOC to PO43--P ratio (from 25:1 to 40:1) effectively eased the carbon deficiency and benefited the proliferation of PAOs. In general, the slow-feeding strategy and sufficiently high carbon input benefited a high and stable EBPR at elevated temperature and represent basic conditions for full-scale applications.


2004 ◽  
Vol 70 (9) ◽  
pp. 5383-5390 ◽  
Author(s):  
Yunhong Kong ◽  
Jeppe Lund Nielsen ◽  
Per Halkjær Nielsen

ABSTRACT The ecophysiology of uncultured Rhodocyclus-related polyphosphate-accumulating organisms (PAO) present in three full-scale enhanced biological phosphorus removal (EBPR) activated sludge plants was studied by using microautoradiography combined with fluorescence in situ hybridization. The investigations showed that these organisms were present in all plants examined and constituted 5 to 10, 10 to 15, and 17 to 22% of the community biomass. The behavior of these bacteria generally was consistent with the biochemical models proposed for PAO, based on studies of lab-scale investigations of enriched and often unknown PAO cultures. Rhodocyclus-related PAO were able to accumulate short-chain substrates, including acetate, propionate, and pyruvate, under anaerobic conditions, but they could not assimilate many other low-molecular-weight compounds, such as ethanol and butyrate. They were able to assimilate two substrates (e.g., acetate and propionate) simultaneously. Leucine and thymidine could not be assimilated as sole substrates and could only be assimilated as cosubstrates with acetate, perhaps serving as N sources. Glucose could not be assimilated by the Rhodocyclus-related PAO, but it was easily fermented in the sludge to products that were subsequently consumed. Glycolysis, and not the tricarboxylic acid cycle, was the source that provided the reducing power needed by the Rhodocyclus-related PAO to form the intracellular polyhydroxyalkanoate storage compounds during anaerobic substrate assimilation. The Rhodocyclus-related PAO were able to take up orthophosphate and accumulate polyphosphate when oxygen, nitrate, or nitrite was present as an electron acceptor. Furthermore, in the presence of acetate growth was sustained by using oxygen, as well as nitrate or nitrite, as an electron acceptor. This strongly indicates that Rhodocyclus-related PAO were able to denitrify and thus played a role in the denitrification occurring in full-scale EBPR plants.


2019 ◽  
Author(s):  
Varun N. Srinivasan ◽  
Guangyu Li ◽  
Dongqi Wang ◽  
Nicholas B. Tooker ◽  
Zihan Dai ◽  
...  

AbstractCandidatusAccumulibacter phosphatis (CAP) and its sub-clades-level diversity has been associated and implicated in successful phosphorus removal performance in enhanced biological phosphorus removal (EBPR). Development of high-throughput untargeted methods to characterize clades of CAP in EBPR communities can enable a better understanding of Accumulibacter ecology at a higher-resolution beyond OTU-level in wastewater resource recovery facilities (WRRFs). In this study, for the first time, using integrated 16S rRNA gene sequencing, oligotyping and genome-resolved metagenomics, we were able to reveal clade-level differences in Accumulibacter communities and associate the differences with two different full-scale EBPR configurations. The results led to the identification and characterization of a distinct and dominant Accumulibacter oligotype - Oligotype 2 (belonging to Clade IIC) and its matching MAG (RC14) associated with side-stream EBPR configuration. We are also able to extract MAGs belonging to CAP clades IIB (RCAB4-2) and II (RC18) which did not have representative genomes before. This study demonstrates and validates the use of a high-throughput approach of oligotyping analysis of 16S rRNA gene sequences to elucidate CAP clade-level diversity. We also show the existence of a previously uncharacterized diversity of CAP clades in full-scale EBPR communities through extraction of MAGs, for the first time from full-scale facilities.


2006 ◽  
Vol 54 (1) ◽  
pp. 111-117 ◽  
Author(s):  
S. He ◽  
A.Z. Gu ◽  
K.D. McMahon

A lab-scale sequencing batch reactor (SBR) and six full-scale wastewater treatment plants (WWTPs) performing enhanced biological phosphorus removal (EBPR) were surveyed. The abundance of Accumulibacter-related organisms in the full-scale plants was investigated using fluorescent in situ hybridization. Accumulibacter-related organisms were present in all of the full-scale EBPR plants, at levels ranging from 9% to 24% of total cells. The high percentage of Accumulibacter-related organisms seemed to be associated with configurations which minimize the nitrate recycling to the anaerobic zone and low influent BOD:TP ratios. PCR-based clone libraries were constructed from the community 16S rRNA gene plus the internally transcribed spacer region amplified from the SBR and five of the full-scale WWTPs. Comparative sequence analysis was carried out using Accumulibacter-related clones, providing higher phylogenetic resolution and revealing finer-scale clustering of the sequences retrieved from the SBR and full-scale EBPR plants.


2006 ◽  
Vol 41 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Zhe Zhang ◽  
Eric R. Hall

Abstract Parameter estimation and wastewater characterization are crucial for modelling of the membrane enhanced biological phosphorus removal (MEBPR) process. Prior to determining the values of a subset of kinetic and stoichiometric parameters used in ASM No. 2 (ASM2), the carbon, nitrogen and phosphorus fractions of influent wastewater at the University of British Columbia (UBC) pilot plant were characterized. It was found that the UBC wastewater contained fractions of volatile acids (SA), readily fermentable biodegradable COD (SF) and slowly biodegradable COD (XS) that fell within the ASM2 default value ranges. The contents of soluble inert COD (SI) and particulate inert COD (XI) were somewhat higher than ASM2 default values. Mixed liquor samples from pilot-scale MEBPR and conventional enhanced biological phosphorus removal (CEBPR) processes operated under parallel conditions, were then analyzed experimentally to assess the impact of operation in a membrane-assisted mode on the growth yield (YH), decay coefficient (bH) and maximum specific growth rate of heterotrophic biomass (µH). The resulting values for YH, bH and µH were slightly lower for the MEBPR train than for the CEBPR train, but the differences were not statistically significant. It is suggested that MEBPR simulation using ASM2 could be accomplished satisfactorily using parameter values determined for a conventional biological phosphorus removal process, if MEBPR parameter values are not available.


1994 ◽  
Vol 29 (7) ◽  
pp. 153-156 ◽  
Author(s):  
D. Wedi ◽  
P. A. Wilderer

Most of the fundamental processes responsible for enhanced biological phosphorus removal (EBPR) were obtained through laboratory tests under defined conditions with pure or enriched cultures. Acinetobacter sp. was identified as the most important group of bacteria responsible for bio-P removal. Full scale data showed, however, that laboratory results do not match full scale results well enough. There is a lack of data on the effects of sub-optimal process conditions such as inadequate availability of volatile fatty acids (VFA), high nitrate recycle, storm water inflow or low temperatures. In this paper the results of full scale experiments on P-release are presented and compared with theoretical values. Measurements at a full scale Phoredox-system showed a surprisingly low P-release in the anaerobic reactor. Only 4 to 10% of the phosphorus in the activated sludge was released in the bulk liquid. With laboratory batch-tests, a maximum of 20% of the P in the sludge could be released. It is assumed that under the prevailing process conditions either the fraction of Acinetobacter sp. was very small, or bacteria other than Acinetobacter sp. were responsible for the P-removal, or most of the phosphorus was bound chemically but mediated by biological processes.


1998 ◽  
Vol 37 (4-5) ◽  
pp. 609-613
Author(s):  
J. Pramanik ◽  
P. L. Trelstad ◽  
J. D. Keasling

Enhanced biological phosphorus removal (EBPR) in wastewater treatment involves metabolic cycling through the biopolymers polyphosphate (polyP), polyhydroxybutyrate (PHB), and glycogen. This cycling is induced through treatment systems that alternate between carbon-rich anaerobic and carbon-poor aerobic reactor basins. While the appearance and disappearance of these biopolymers has been documented, the intracellular pressures that regulate their synthesis and degradation are not well understood. Current models of the EBPR process have examined a limited number of metabolic pathways that are frequently lumped into an even smaller number of “reactions.” This work, on the other hand, uses a stoichiometric model that contains a complete set of the pathways involved in bacterial biomass synthesis and energy production to examine EBPR metabolism. Using the stoichiometric model we were able to analyze the role of EBPR metabolism within the larger context of total cellular metabolism, as well as predict the flux distribution of carbon and energy fluxes throughout the total reaction network. The model was able to predict the consumption of PHB, the degradation of polyP, the uptake of acetate and the release of Pi. It demonstrated the relationship between acetate uptake and Pi release, and the effect of pH on this relationship. The model also allowed analysis of growth metabolism with respect to EBPR.


2000 ◽  
Vol 41 (4-5) ◽  
pp. 503-508 ◽  
Author(s):  
R.F. Gonçalves ◽  
F. Rogalla

This work describes laboratory scale research about Enhanced Biological Phosphorus Removal (EBPR) in a submerged biofilter under Anaerobic/Oxic (A/O) alternation and continuous feed. Its main purpose is to detail the behaviour of the reactor throughout the anaerobic and the aerobic phases of the A/O cycle, to study the importance of the anaerobic phase in the selection of the EBPR bacteria in the biofilm and to evaluate the consumption and the importance of the organic substrate during the anaerobic phase. The mass balance over the Phosphorus (P) element indicates that long anaerobic phases (6 h) are more efficient than short ones (3 h) as a selector of EBPR bacteria in biofilms. In both comparisons, thespecific mass of P released in a 6 h period represents almost 50% more than the amount of P release in the shorter period (3 h). However, the presence of rapidly biodegradable COD in the influent of the anaerobic phase is a more effective selector, more important than the duration of the anaerobic phase: by doubling the amount of acetic acid in the influent, a similar 50% increase of P-release can be achieved at short anaerobic periods of 3 h. The effect of the strategy adopted in this study, focusing on selecting EBPR bacteria in biofilm, is shown by the P levels of 4% (total P/SST) in the sludge removed from the BF by backwashing in all periods.


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