Showing papers on "Dechloromonas published in 2016"

Correlating microbial community compositions with environmental factors in activated sludge from four full-scale municipal wastewater treatment plants in Shanghai, China.

Abstract: Activated sludge system is an important process of domestic and industrial wastewater treatment containing highly diverse microbial communities. In this study, high-throughput sequencing was applied to examine the microbial community composition and diversity of activated sludge samples from four full-scale municipal wastewater treatment plants (WWTPs) in Shanghai. A relationship between microbial communities and environmental variables was examined. Proteobacteria was the most dominant phylogenetic group, followed by Bacteroidetes and Firmicutes. A total of 166 genera were commonly shared by all seven sludge samples, including Zoogloea, Dechloromonas, Thauera, Nitrospira, Arcobacter, etc. Besides these shared populations, certain unique bacterial populations were found abundant in individual sludge sample. Canonical correspondence analysis (CCA) indicated that influent COD and pH had the greatest influence on microbial community compositions, whereas dissolved oxygen (DO) exhibited the least influence. The operating process was likely to foster diversity of the microbial communities inhabiting the wastewater treatment facilities. Alternative operation methods including a fluctuation of anoxic, oxic, and anaerobic conditions were favorable for promoting the growth of diverse microbial populations in activated sludge systems.

Changes in the composition and diversity of microbial communities during anaerobic nitrate reduction and Fe(II) oxidation at circumneutral pH in paddy soil

Abstract: Kinetics of nitrate (NO3−) reduction and ferrous iron (Fe(II)) oxidation in paddy soil were investigated under anoxic conditions at circumneutral pH using three different treatments (i.e., Lactate + Fe(II), Lactate + NO3−, and Lactate + NO3− + Fe(II)). The results revealed that NO3− could be rapidly reduced to nitrite (NO2−) within two days in treatments of Lactate + NO3− and Lactate + NO3− + Fe(II), and the presence of Fe(II) facilitated the NO2− reduction. Whereas no obvious Fe(II) oxidation was observed in treatment of Lactate + Fe(II), Fe(II) oxidation took place only when NO3− was added. Illumina high-throughput sequencing used to profile the diversity and abundance of microbial communities showed that the phyla of Proteobacteria and Firmicutes had a dominant presence in all three treatments with lactate. Acidaminobacter, Proteiniclasticum, Alkaliphilus, and Natronincola_Anaerovirgula were found to be the dominant genera during NO3− reduction without Fe(II) after addition of lactate, and all were seldom reported to be associated with NO3− reduction. Azospira, Zoogloea, and Dechloromonas dominated during NO3− reduction in the presence of Fe(II), and all are betaproteobacterial NO3−-reducing bacteria that do not produce ammonium as end products of NO3− reduction. Whereas Azospira, Zoogloea, and Dechloromonas have been isolated or identified from NO3−-reducing Fe(II) oxidation culture previously, the NO2− produced by these NO3− reducing bacteria can also oxidize Fe(II) abiotically, resulting in facilitated NO2− disappearance in the treatment of Lactate + NO3− + Fe(II). These findings increase our understanding of the processes of NO3− reduction in the absence and presence of Fe(II) in anoxic paddy soil at circumneutral pH and extend our knowledge of the microbial communities involved in these processes.

Culture-Dependent and -Independent Identification of Polyphosphate-Accumulating Dechloromonas spp. Predominating in a Full-Scale Oxidation Ditch Wastewater Treatment Plant.

Abstract: The oxidation ditch process is one of the most economical approaches currently used to simultaneously remove organic carbon, nitrogen, and also phosphorus (P) from wastewater. However, limited information is available on biological P removal in this process. In the present study, microorganisms contributing to P removal in a full-scale oxidation ditch reactor were investigated using culture-dependent and -independent approaches. A microbial community analysis based on 16S rRNA gene sequencing revealed that a phylotype closely related to Dechloromonas spp. in the family Rhodocyclaceae dominated in the oxidation ditch reactor. This dominant Dechloromonas sp. was successfully isolated and subjected to fluorescent staining for polyphosphate, followed by microscopic observations and a spectrofluorometric analysis, which clearly demonstrated that the Dechloromonas isolate exhibited a strong ability to accumulate polyphosphate within its cells. These results indicate the potential key role of Dechloromonas spp. in efficient P removal in the oxidation ditch wastewater treatment process.

Community dynamics of denitrifying bacteria in full-scale wastewater treatment plants.

Abstract: Effective and stable nitrogen removal from wastewater requires abundant and active denitrifying populations. In this study, a one-year investigation of the population dynamics of phylogenetic groups known to harbor nitrate reducers was conducted in three municipal wastewater treatment plants (WWTPs). The bacterial community composition was determined by amplicon sequencing of the 16S rRNA gene, and putative nitrate reducers were identified by sequencing narG and napA genes. Fluorescence in situ hybridization with oligonucleotide probes targeting known nitrate reducers in wastewater revealed that certain bacteria predominated in the WWTPs: Curvibacter-related bacteria, Comamonadaceae, Azoarcus, Thauera, Dechloromonas, and Candidatus Accumulibacter within Rhodocyclaceae. The data showed high diversity in the nitrate-reducing community and a large degree of redundancy, with a relatively stable core group of bacteria in each plant that ensured small yearly variation in nitrate reduction rates.

Biological denitrification using poly(butanediol succinate) as electron donor.

Abstract: Poly(butanediol succinate) (PBS), a biodegradable polymer, was used as both solid carbon source and biofilm carrier for biological nitrate removal process, in which PBS was filled in a packed-bed bioreactor. The denitrification performance and the microbial diversity of biofilm attached on the surface of PBS were investigated. The experimental results showed that the volumetric denitrification rate was 0.60 kg m(-3) day(-1) when NO3-N loading rate was 0.63 kg m(-3) day(-1), and the average NO2-N concentration was below 0.20 mg L(-1). The effluent pH value decreased slightly from a range of 6.98-7.87 to 6.46-7.18. The analysis of microbial community structure of biofilm by pyrosequencing method showed that Proteobacteria was the most abundant phylum (89.87 %), and β-Proteobacteria represented the most abundant class. Among the 76 identified genera, Dechloromonas (10.26 %), Alicycliphilus (9.15 %), Azospira (8.92 %), and Sinobacteraceae-uncultured (8.75 %) were the abundant genera. PBS, as a promising alternative carbon source, is a suitable solid carbon source and biofilm carrier for nitrate removal.

Hydrogen-fed biofilm reactors reducing selenate and sulfate: Community structure and capture of elemental selenium within the biofilm.

Abstract: Remediation of selenate (SeO4 (2-) ) contamination through microbial reduction is often challenging due to the presence of sulfate (SO4 (2-) ), which can lead to competition for the electron donor and the co-production of toxic H2 S. Microbial reduction of SeO4 (2-) in the presence of SO4 (2-) was studied in two hydrogen-based membrane biofilm reactors (MBfRs). One MBfR was initiated with SO4 (2-) -reducing conditions and gradually shifted to SeO4 (2-) reduction. The second MBfR was developed with a SeO4 (2-) -reducing biofilm, followed by SO4 (2-) introduction. Biofilms within both MBfRs achieved greater than 90% SeO4 (2-) reduction, even though the SeO4 (2-) concentration ranged from 1,000-11,000 μg/L, more than 20-200 times the maximum contaminant level for drinking water (50 μg/L). Biofilm microbial community composition, assessed by 16S rRNA gene-based amplicon pyrosequencing, was distinct between the two MBfRs and was framed by alterations in SeO4 (2-) loading. Specifically, high SeO4 (2-) loading resulted in communities mainly composed of denitrifying bacteria (e.g., Denitratisoma and Dechloromonas). In contrast, low loading led to mostly sulfate-reducing bacteria (i.e., Desulfovibrio) and sulfur-oxidizing bacteria (i.e., Sulfuricurvum and Sulfurovum). SeO4 (2-) was reduced to elemental selenium (Se°), which was visualized within the biofilm as crystalloid aggregates, with its fate corresponding to that of biofilm solids. In conclusion, microbial biofilm communities initiated under either SeO4 (2-) or SO4 (2-) -reducing conditions attained high SeO4 (2-) removal rates even though their microbial community composition was quite distinct. Biotechnol. Bioeng. 2016;113: 1736-1744. © 2016 Wiley Periodicals, Inc.

Microbial diversity and community structure of denitrifying biological filters operated with different carbon sources.

Abstract: The treatment performance and spatial microbial community structure of three parallel denitrifying biological filters (DNBFs) operated with methanol, ethanol and acetate, respectively, were explored. The acetate-fed DNBF presented the highest denitrification rate and NOx-N (NO2-N and NO3-N) removal efficiency, while the methanol-fed DNBF showed the lowest carbon consumption and NOx-N removal efficiency. Distinct spatial distribution patterns of terminal restriction fragment length polymorphism fingerprints were observed among the DNBFs. The ethanol enhanced captured biofilms throughout the flowpath of DNBF had the highest diversity and evenness. The methanol-enhanced attached biofilm along the flowpath presented the highest evenness, but lowest richness and limited diversity. β-Proteobacteria was dominant in the microbial community in all of methanol, ethanol and acetate enhanced biofilm; however, different external carbon sources resulted in different dominant genera species. Thauera was dominant in the acetate enhanced bacterial community, while both Dechloromonas and Thauera were dominant in that of ethanol fed. However, methylotrophic bacteria (Methyloversatilis and Methylotenera) dominated exclusively in the methanol enhanced bacterial community throughout of the DNBF.

Bioremediation of nitrate and Fe(ii) combined contamination in groundwater by heterotrophic denitrifying bacteria and microbial community analysis

Abstract: Species of denitrifying bacteria are capable of nitrate reducing and Fe(II) oxidizing. The optimal temperature, pH and C/N ratio for denitrification coupled with Fe(II) oxidation in circumneutral anaerobic groundwater was investigated by a Box–Behnken design and response surface methodology. The microbial diversities were analyzed by high-throughput sequencing. The results showed that the optimal condition was achieved at a temperature of 24.93 °C, pH of 7.23 and C/N ratio of 1.43, at which almost 100% of nitrate-N and Fe(II) was removed with little byproduct accumulation. Within the temperature range 15–25 °C, pH 7–8.25 and C/N ratio 1.23–1.47, both nitrate and Fe(II) concentration could be removed effectively. The distributions of the microbial taxonomy composition (e.g., phylum, genus) differed under different temperatures, pH values and C/N ratios. Betaproteobacteria and Bacteroidetes dominated the bacterial phyla, and Methyloversatilis was the predominant bacterial genus in the enrichment cultures. Complex species of bacteria were attributed to the sophisticated reaction system. Though heterotrophic denitrification and Fe(II) oxidation dominated the system, autotrophic denitrification, H2 and acetate production may, somehow, have contributed to the entire reaction system. Denitrifiers (e.g., Azonexus), bacteria capable of nitrate dependent Fe(II) oxidation (NDFO) (e.g., Dechloromonas) and bacteria which could produce acetate as co-substrates for NDFO (e.g., Acetobacterium) were unevenly distributed. These findings provide support for nitrate and Fe(II) contaminated groundwater bioremediation, and a better understanding of the microbial ecosystem of the enriched heterotrophic denitrifiers.

Dynamics of the diversity and structure of the overall and nitrifying microbial community in activated sludge along gradient copper exposures

Abstract: Diversity and composition of the microbial community, especially the nitrifiers, are essential to the treatment efficiency of wastewater in activated sludge systems. Heavy metals commonly present in the wastewater influent such as Cu can alter the community structure of nitrifiers and lower their activity. However, the dynamics of microbial community along a gradient of metal exposure have largely been unexplored, partially due to the limitations in traditional molecular methods. This study explored the dynamics regarding the diversity and community structures of overall and nitrifying microbial communities in activated sludge under intermittent Cu gradient loadings using Illumina sequencing. We created a new local nitrifying bacterial database for sequence BLAST searches. High Cu loadings (>10.9 mg/L) impoverished microbial diversity and altered the microbial community. Overall, Proteobacteria was the predominant phylum in the activated sludge system, in which Zoogloea, Thauera, and Dechloromonas (genera within the Rhodocyclaceae family of the Beta-proteobacteria class) were the dominant genera in the presence of Cu. The abundance of unclassified bacteria at the phylum level increased substantially with increasing Cu loadings. Nitrosomonas and Nitrospira were the predominant nitrifiers. The nitrifying bacterial community changed through increasing abundance and shifting to Cu-tolerant species to reduce the toxic effects of Cu. Our local nitrifying bacterial database helped to improve the resolution of bacterial identification. Our results provide insights into the dynamics of microbial community in response to various metal concentrations in activated sludge systems and improve our understanding regarding the effect of metals on wastewater treatment efficiency.

Evaluation of electron donors for biological perchlorate removal highlights the importance of diverse perchlorate-reducing populations

Abstract: This research investigated the treatment of a synthetic groundwater with approximately 100 mg L−1 perchlorate (ClO4−) and 15 mg L−1 nitrate (NO3−-N) using a bench-scale, fluidized-bed bioreactor (FBR). The groundwater was amended sequentially with acetate and MicroC2000™, a proprietary, glycerol-based electron donor. Nitrate reduction to less than 0.05 mg L−1 NO3−-N and perchlorate removal to less than 0.3 mg L−1 ClO4− occurred under both electron donor regimes, although a higher biomass yield was observed and a higher influent COD concentration was required to maintain the same effluent quality when MicroC2000™ was used as the electron donor. High-throughput sequencing of partial 16S rRNA genes from biomass collected at several time points revealed that a single Dechloromonas population dominated the perchlorate-reducing community under both electron donors and Dechloromonas species comprised greater than 30% relative abundance of the bacterial community by the end of reactor operation. The same Dechloromonas population was abundant in two bench-scale systems fed lower perchlorate concentrations, although several other perchlorate-reducing bacteria, presumably with higher affinities for perchlorate, were also abundant in those systems. The results suggest that to reduce perchlorate to levels that allow groundwater to serve as a drinking water source, distinct environments for diverse perchlorate-reducing bacteria with high and low affinities for perchlorate are needed. Such conditions can be created by using two bioreactors in series.

Microbiote shift in sequencing batch reactors in response to antimicrobial ZnO nanoparticles

Abstract: Zinc oxide nanoparticles (ZnO NPs) have been monitored in wastewater treatment plants as their potential adverse effects on functional microorganisms have been causing increasing concern. In this study, the effects of ZnO NPs on the microbial community and the characterization of resistant/sensitive genera to ZnO NPs toxicity were investigated in sequencing batch reactors. Our results showed that ZnO NPs induced a moderate decrease in COD and nitrogen and phosphorus removal under a mid-long-term exposure. The predominant bacterial phyla were Bacteroidetes and Proteobacteria. With an increase in ZnO concentrations, the proportion of Bacteroidetes decreased, whereas that of Proteobacteria increased. Further investigations indicated that Chryseobacterium and Dechloromonas exhibit high tolerance to ZnO NPs, whereas the genera Sediminibacterium and Blvii28 exhibit specific vulnerability to ZnO NPs.

Comparison of microbial community structure in a biological nutrient removal process at various stages of operation

Abstract: In this study, the modified five-stage Bardenpho process was used for the treatment of domestic wastewater in a pilot-scale reactor with an active volume of 8.6 m3. The hydraulic retention time of the process was 16 h and the sludge retention time was 15 d. The removal efficiencies for chemical oxygen demand, total Kjeldahl nitrogen, ammonia nitrogen (NH3–N), total phosphorus, phosphate phosphorus (PO4-P), suspended solids, and volatile suspended solids were obtained as 87 ± 5%; 86 ± 12%; 93 ± 14%; 89 ± 9%; 88 ± 8%; 94 ± 4%, and 94 ± 4%, respectively. The microbial community was also determined in the process by PCR–DGGE–Sequencing molecular techniques. While Nitrosomonas sp., Nitrosospira sp., Nitrosomonas europaea, Dechloromonas sp., Candidatus Accumulibacter sp., Bacteroidetes bacterium, Firmicutes were observed during the start-up period, Nitrosomonas sp., Nitrosospira sp., N. europaea, Dechloromonas sp., C. accumulibacter sp. were observed after the steady-state period.