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1.
Chemosphere ; 276: 130250, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34088103

RESUMO

In this study, a woodchip biofilm electrode reactor (WBER) with woodchips embedded anode and cathode was developed, and its denitrification mechanism was analyzed by investigating the denitrification performance, organic matter change, redox environment and microbial community. The results show that the WBER with a carbon rod as anode (C-WBER) had a higher denitrification efficiency (2.58 mg NO- 3-N/(L·h)) and lower energy consumption (0.012 kWh/g NO- 3-N) at 350 mA/m2. By reducing the hydroxyl radical and dissolved oxygen concentrations, anode embedding technology effectively decreased the inhibition on microorganisms. Lignin decomposition, nitrification and aerobic denitrification were carried out in anode. Additionally, hydrogen autotrophic denitrification and heterotrophic denitrification were occurred in cathode. The WBER effectively removed nitrate and reduced the cost, providing a theoretical basis and direction for further develop BERs.


Assuntos
Nitratos , Purificação da Água , Processos Autotróficos , Biofilmes , Reatores Biológicos
2.
Chemosphere ; 278: 130413, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33823349

RESUMO

The study was based on the removal of nitrate and sulfide, and aimed to nitrite accumulation. The process of autotrophic denitrification driven by sulfide as an electron donor was investigated in a sequencing batch reactor. The research showed that autotrophic denitrification successfully started on day 22, and the removal rates of NO3--N and S2--S were 95.8% and 100%, respectively, when the S/N molar ratio was 1.45. When the S/N ratio was reduced to 0.94, the phenomenon of NO2--N accumulation was observed. NO2--N continuously accumulated, and the maximum accumulation rate was 55.3% when the S/N ratio was 0.8. In the batch test, the study showed that NO2--N accumulation was optimal when the S/N ratio was 0.8, and the NO2--N concentration increased with increasing NO3--N concentration at the same S/N ratio. Microbial communities also changed based on the high-throughput analysis, and Proteobacteria (59.5%-84%) was the main phylum. Arenimonas (11.4%-28.2%) and uncultured_f_ Chromatiaceae (5.7%-27.5%) were the dominant bacteria, which complete denitrification and desulfurization throughout the operating system. Therefore, this study provided a theoretical basis for the simultaneous removal of NO3--N and S2--S, as well as the accumulation of nitrite, and provided material support for anaerobic ammonia oxidation technology.


Assuntos
Nitratos , Nitritos , Processos Autotróficos , Reatores Biológicos , Desnitrificação , Nitrogênio , Sulfetos , Enxofre
3.
Chemosphere ; 278: 130460, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33838412

RESUMO

The autotrophic iron-depended denitrification (AIDD), triggered by microelectrolysis, was established in the microelectrolysis-assistant up-flow anaerobic sludge blanket (MEA-UASB) with the purpose of low-strength coal gasification wastewater (LSCGW) treatment while control UASB operated in parallel. The results revealed that chemical oxygen demand (COD) removal efficiency and total nitrogen (TN) removal load at optimum current (2.5 A/m3) in MEA-UASB (83.2 ± 2.6% and 0.220 ± 0.010 kg N/m3·d) were 1.42-fold and 1.57-fold higher than those (58.5 ± 2.1% and 0.139 ± 0.011 kg N/m3·d) in UASB, verifying that AIDD and following dissimilatory iron reduction (DIR) process could offer the novel pathway to solve the electron donor-deficient and traditionally denitrification-infeasible problems. High-throughput 16S rRNA gene pyrosequencing shown that iron-oxidizing denitrifiers (Thiobacillus and Acidovorax species) and iron reducing bacteria (Geothrix and Ignavibacterium speices), acted as microbial iron cycle of contributors, were specially enriched at optimum operating condition. Additionally, the activities of microbial electron transfer chain, electron transporters (complex I, II, III and cytochrome c) and abundance of genes encoding important enzymes (narG, nirK/S, norB and nosZ) were remarkably promoted, suggesting that electron transport and consumption capacities were stimulated during denitrification process. This study could shed light on better understanding about microelectrolysis-triggered AIDD for treatment of refractory LSCGW and further widen its application potential in the future.


Assuntos
Desnitrificação , Águas Residuárias , Processos Autotróficos , Reatores Biológicos , Carvão Mineral , Compostos Férricos , Compostos Ferrosos , Nitratos , Nitrogênio , RNA Ribossômico 16S/genética , Eliminação de Resíduos Líquidos
4.
Bioresour Technol ; 329: 124918, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33684839

RESUMO

Sulfur-driven autotrophic denitrification (SDAD) is feasible for the treatment of low-C/N-ratio and sulfur-laden wastewaters. The nitrite accumulated in SDAD will affect the performance and stability of the system but can be a potential electron acceptor. Thus, single- and multiple-electron acceptor-mediated SDAD systems were investigated. Batch assays revealed that nitrite and nitrate were the preferential options in the SDAD system with single and multiple electron acceptors, respectively. Synchronous nitrogen and sulfur removal was successfully achieved in continuous flow experiments with multiple electron acceptors, and the system could adapt well to high concentrations of sulfide, nitrate and nitrite (i.e., 720, 108 and 64.8 mg L-1, respectively), with the predominant genera shifting from Thiobacillus (48.88%) at the initial stage to unclassified_p_Firmicute (34.24%) and Syner-01 (12.31%) at the last stage. This work provides a fundamental basis for applying and regulating SDAD with multiple electron acceptors for the remediation of nitrogen- and sulfide- laden wastewaters.


Assuntos
Microbiota , Nitrogênio , Processos Autotróficos , Reatores Biológicos , Desnitrificação , Elétrons , Nitratos , Enxofre
5.
Bioresour Technol ; 329: 124866, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33647604

RESUMO

This study aimed to reveal whether Cupriavidus necator H16 is suited for the production of acetoin based on the carboxylic acids acetate, butyrate and propionate under heterotrophic and mixotrophic conditions. The chosen production strain, lacking the polyhydroxybutyrate synthases phaC1 and phaC2, was revealed to be beneficiary for autotrophic acetoin production. Proteomic analysis of the strain determined that the deletions do indeed have a significant impact on pyruvate formation and its subsequent direction towards the introduced acetoin-synthesis pathway. Moreover, the strain was tested for its ability to use typical dark fermentation products under hetero- and mixotrophic conditions. Growth with butyrate and acetate led to low efficiencies, while 46.54% ±0.78 of the added propionate was converted into acetoin. Interestingly, mixotrophic conditions led to simultaneous consumption of acetate and butyrate with the gaseous substrates and lowered efficiency. In contrast, mixotrophic propionate consumption led to diauxic behavior and high carbon efficiency of 71.2% ±0.64.


Assuntos
Acetoína , Cupriavidus necator , Processos Autotróficos , Processos Heterotróficos , Proteômica
6.
Bioresour Technol ; 329: 124925, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33676352

RESUMO

In this study, an integrated device with scrubbing and biochemical treatment functions was used, and partial nitrification (PN)-Anammox and sulfur autotrophic denitrification (SADN) processes were coupled in a biochemical treatment pond to explore the feasibility of in-situ autotrophic removal of NH3 and H2S. The results showed that the removal efficiency of NH3 and H2S in waste gas are 95% and 87.5% respectively. The scrubbing liquid was efficiently treated in the biochemical treatment pond. Nitrogenous compounds weren't accumulated in liquid and converted to N2 by SADN and PN-Anammox coupling system. S2- was mainly used by SADN process to reduce NO3-. The scrubbing liquid processed by the biochemical treatment pond was refluxed to the scrubber to achieve continuous absorption of NH3 and H2S. Microbial community and functional microbial analysis showed that the PN-Anammox and SADN processes were the main processes to achieve the conversion of pollutants in the scrubbing liquid.


Assuntos
Desnitrificação , Nitrificação , Processos Autotróficos , Reatores Biológicos , Nitrogênio/análise , Oxirredução , Enxofre , Águas Residuárias
7.
Nat Commun ; 12(1): 830, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33547297

RESUMO

In marine and freshwater oxygen-deficient zones, the remineralization of sinking organic matter from the photic zone is central to driving nitrogen loss. Deep blooms of photosynthetic bacteria, which form the suboxic/anoxic chlorophyll maximum (ACM), widespread in aquatic ecosystems, may also contribute to the local input of organic matter. Yet, the influence of the ACM on nitrogen and carbon cycling remains poorly understood. Using a suite of stable isotope tracer experiments, we examined the transformation of nitrogen and carbon under an ACM (comprising of Chlorobiaceae and Synechococcales) and a non-ACM scenario in the anoxic zone of Lake Tanganyika. We find that the ACM hosts a tight coupling of photo/litho-autotrophic and heterotrophic processes. In particular, the ACM was a hotspot of organic matter remineralization that controlled an important supply of ammonium driving a nitrification-anammox coupling, and thereby played a key role in regulating nitrogen loss in the oxygen-deficient zone.


Assuntos
Ciclo do Carbono/fisiologia , Carbono/química , Chlorobi/metabolismo , Ciclo do Nitrogênio/fisiologia , Nitrogênio/química , Synechococcus/metabolismo , Compostos de Amônio/química , Compostos de Amônio/metabolismo , Anaerobiose/fisiologia , Processos Autotróficos , Carbono/metabolismo , Chlorobi/química , Clorofila/química , Clorofila/metabolismo , República Democrática do Congo , Ecossistema , Marcação por Isótopo , Lagos/química , Lagos/microbiologia , Nitrificação/fisiologia , Nitrogênio/metabolismo , Oxirredução , Synechococcus/química , Tanzânia
8.
Sci Data ; 8(1): 51, 2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33563990

RESUMO

Acetogens are anaerobic bacteria that utilise gaseous feedstocks such as carbon monoxide (CO) and carbon dioxide (CO2) to synthesise biomass and various metabolites via the energetically efficient Wood-Ljungdahl pathway. Because of this pathway, acetogens have been considered as a novel platform to produce biochemicals from gaseous feedstocks, potentially replacing the conventional thermochemical processes. Despite their advantages, a lack of systematic understanding of the transcriptional and translational regulation in acetogens during autotrophic growth limits the rational strain design to produce the desired products. To overcome this problem, we presented RNA sequencing and ribosome profiling data of four acetogens cultivated under heterotrophic and autotrophic conditions, providing data on genome-scale transcriptional and translational responses of acetogens during CO2 fixation. These data facilitate the discovery of regulatory elements embedded in their genomes, which could be utilised to engineer strains to achieve better growth and productivity. We anticipate that these data will expand our understanding of the processes of CO2 fixation and will help in the designing of strains for the desired biochemical production.


Assuntos
Processos Autotróficos , Bactérias/metabolismo , Dióxido de Carbono/metabolismo , Processos Heterotróficos , Transcriptoma , Ciclo do Carbono , RNA-Seq
9.
Artigo em Inglês | MEDLINE | ID: mdl-33540891

RESUMO

The contribution ratio of autotrophic and heterotrophic metabolism in the mixotrophic culture of Chlorella sorokiniana (C. sorokiniana) was investigated. At the early stage of mixotrophic growth (day 0-1), autotrophy contributed over 70% of the total metabolism; however, heterotrophy contributed more than autotrophy after day 1 due to the rapid increase in cell density, which had a shading effect in the photo-bioreactor. Heterotrophy continued to have a higher contribution until the available organic carbon was depleted at which point autotrophy became dominant again. Overall, the increase in algal biomass and light conditions in the photo-bioreactor are important factors in determining the contribution of autotrophy and heterotrophy during a mixotrophic culture.


Assuntos
Chlorella , Microalgas , Processos Autotróficos , Biomassa , Ciclo do Carbono , Processos Heterotróficos
10.
Bioresour Technol ; 328: 124848, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33611020

RESUMO

This study investigated the performance and microbiome of cyclic denitrification filters (CDFs) for wood and sulfur heterotrophic-autotrophic denitrification (WSHAD) of saline wastewater. Wood-sulfur CDFs integrated into two pilot-scale marine recirculating aquaculture systems achieved high denitrification rates (103 ± 8.5 g N/(m3·d)). The combined use of pine wood and sulfur resulted in lower SO42- accumulation compared with prior saline wastewater denitrification studies with sulfur alone. Although fish tank water quality parameters, including ammonia, nitrite, nitrate and sulfide, were below the inhibitory levels for marine fish production, lower survival rates of Poecilia sphenops were observed compared with prior studies. Heterotrophic denitrification was the dominant removal mechanism during the early operational stages, while sulfur autotrophic denitrification increased as readily biodegradable organic carbon released from wood chips decreased over time. 16S rRNA-based analysis of the CDF microbiome revealed that Sulfurimonas, Thioalbus, Defluviimonas, and Ornatilinea as notable genera that contributed to denitrification performance.


Assuntos
Desnitrificação , Águas Residuárias , Animais , Processos Autotróficos , Reatores Biológicos , Nitratos , Nitrogênio , RNA Ribossômico 16S/genética , Enxofre , Madeira
11.
Appl Environ Microbiol ; 87(9)2021 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-33608294

RESUMO

Depressurization and sample processing delays may impact the outcome of shipboard microbial incubations of samples collected from the deep sea. To address this knowledge gap, we developed a remotely operated vehicle (ROV)-powered incubator instrument to carry out and compare results from in situ and shipboard RNA stable isotope probing (RNA-SIP) experiments to identify the key chemolithoautotrophic microbes and metabolisms in diffuse, low-temperature venting fluids from Axial Seamount. All the incubations showed microbial uptake of labeled bicarbonate primarily by thermophilic autotrophic Epsilonbacteraeota that oxidized hydrogen coupled with nitrate reduction. However, the in situ seafloor incubations showed higher abundances of transcripts annotated for aerobic processes, suggesting that oxygen was lost from the hydrothermal fluid samples prior to shipboard analysis. Furthermore, transcripts for thermal stress proteins such as heat shock chaperones and proteases were significantly more abundant in the shipboard incubations, suggesting that depressurization induced thermal stress in the metabolically active microbes in these incubations. Together, the results indicate that while the autotrophic microbial communities in the shipboard and seafloor experiments behaved similarly, there were distinct differences that provide new insight into the activities of natural microbial assemblages under nearly native conditions in the ocean.IMPORTANCE Diverse microbial communities drive biogeochemical cycles in Earth's ocean, yet studying these organisms and processes is often limited by technological capabilities, especially in the deep ocean. In this study, we used a novel marine microbial incubator instrument capable of in situ experimentation to investigate microbial primary producers at deep-sea hydrothermal vents. We carried out identical stable isotope probing experiments coupled to RNA sequencing both on the seafloor and on the ship to examine thermophilic, microbial autotrophs in venting fluids from an active submarine volcano. Our results indicate that microbial communities were significantly impacted by the effects of depressurization and sample processing delays, with shipboard microbial communities being more stressed than seafloor incubations. Differences in metabolism were also apparent and are likely linked to the chemistry of the fluid at the beginning of the experiment. Microbial experimentation in the natural habitat provides new insights into understanding microbial activities in the ocean.


Assuntos
Técnicas Bacteriológicas/métodos , Fontes Hidrotermais/microbiologia , Microbiota/genética , Processos Autotróficos , Bactérias/genética , Sequência de Bases , Metagenoma , Pressão , RNA Ribossômico 16S/genética , Água do Mar , Navios , Fatores de Tempo
12.
Sci Total Environ ; 774: 145136, 2021 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-33609842

RESUMO

The autotrophic nitrogen removal process has great potential to be applied to the biological removal of nitrogen from wastewater, but its application is hindered by its unstable operation under adverse environmental conditions, such as those presented by low temperatures, high organic matter concentrations, or the presence of toxic substances. Granules and microbial entrapment technology can effectively retain and enrich microbial assemblages in reactors to improve operating efficiency and reactor stability. The carriers can also protect the reactor's internal microorganisms from interference from the external environment. This article critically reviews the existing literature on autotrophic nitrogen removal systems using immobilization technology. We focus our discussion on the natural aggregation process (granulation) and entrapment technology. The selection of carrier materials and entrapment methods are identified and described in detail and the mechanisms through which entrapment technology protects microorganisms are analyzed. This review will provide a better understanding of the mechanisms through which immobilization operates and the prospects for immobilization technology to be applied in autotrophic nitrogen removal systems.


Assuntos
Desnitrificação , Nitrogênio , Processos Autotróficos , Reatores Biológicos , Esgotos , Eliminação de Resíduos Líquidos
13.
Water Sci Technol ; 83(1): 63-76, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33460407

RESUMO

Biofilms were cultivated for a 68-day period under different hydrodynamic conditions, and the effect of hydrodynamics on the succession of autotrophic and heterotrophic organisms of biofilms was investigated. Five obvious stages were observed during biofilm formation. At Stage I, the attachment of algae was delayed, especially under turbulent conditions. After Stage II, algal density and heterotrophic biomass of biofilms increased, which were obvious under turbulent flow. Therefore, the algal density and heterotrophic biomass of biofilms were largest under turbulent condition, followed by laminar condition, and then transitional condition. Diatoms were dominant in all flumes and were most abundant under turbulent conditions. The proportion of cyanobacteria was highest under laminar conditions. The ratio of aerobic to anaerobic bacteria decreased and their co-existence could facilitate the nitrification and denitrification in the biofilm. The ratio of monounsaturated fatty acids to saturated fatty acids was highest under turbulent conditions on the 15th day. While the ratio was highest under laminar condition on the 48th day, the high ratio indicates the high ability of biofilm to obtain nutrients, which affect the growth of algae. The regulation of hydrodynamics is a useful technology which can affect the growth of the microorganisms of biofilm, and further improve water quality.


Assuntos
Hidrodinâmica , Rios , Processos Autotróficos , Biofilmes , Ecossistema
14.
Arch Microbiol ; 203(4): 1439-1450, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33392625

RESUMO

Chlamydomonas reinhardtii is one of the most characterized green algae. The open-pond cultivation can be challenging due to sensitivity of strain to fluctuating environmental conditions and unavailability of low-cost photoautotrophic media. In this study, the photoautotrophic growth of C. reinhardtii was evaluated in 1-m2 open ponds placed in greenhouse. Sodium bicarbonate (NaHCO3) was evaluated as an alternative buffering agent to tris. The effect of buffer and pH was tested. The growth was studied in the presence of various nitrogen [urea and ammonium bicarbonate (NH4HCO3)] sources. In the study, it was found that 125-ppm NaHCO3 as an optimum concentration. The buffering agent in the media was found to have major impact on growth. Without buffering agent, culture did not grow, and pH drop was observed. The sodium bicarbonate-buffered media reported to have the lowest bacterial contamination (18.3%), highest AFDW per OD (0.39 ± 0.027 g/L) and higher Fv/Fm (0.714 ± 0.016), whereas these values were found to be 62%, 0.19 ± 0.02 g/L and 0.537 ± 0.053 for tris-grown culture, respectively. The pH 7.0-7.5 was determined as an optimum, whereas pH 6.5-7.0 and 8.0-8.5 were found to affect the growth and induce palmelloidy. The OD and AFDW of culture grown in NH4HCO3 were found equivalent to a standard nitrogen source (NH4Cl), whereas culture shown poor growth in urea. Based on these data, NH4HCO3 media recipe and the optimized cultivation parameters were selected for photoautotrophic cultivation of Chlamydomonas in greenhouse open ponds.


Assuntos
Processos Autotróficos , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Processos Fototróficos , Lagoas/química , Chlamydomonas reinhardtii/metabolismo , Meios de Cultura/química , Concentração de Íons de Hidrogênio , Nitrogênio/análise , Bicarbonato de Sódio/análise
15.
J Hazard Mater ; 411: 125151, 2021 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-33485237

RESUMO

In a lab-scale anaerobic baffled reactor (ABR) with eight compartments, the heterotrophic and sulfur autotrophic processes were combined to remove perchlorate. And then, the step-feeding distribution ratio of the heterotrophic perchlorate reduction unit (HPR unit) was optimized to achieve efficient removal of high concentration perchlorate. Under the optimized step-feeding distribution ratio, the perchlorate removal efficiency reached to 99.8% with the influent concentration of 1300 mg/L, indicating that the removal performance of step-feeding was better than that of normal-feeding. A mass balance results showed that the perchlorate removal capacity of the C1-C5 compartments were 11.8 ± 0.6, 13.2 ± 0.2, 11.7 ± 1.0, 8.8 ± 0.2 and 9.8 ± 1.0 g/d during the stage VIII, indicating that the step-feeding can effectively relieve pollutant loading of C1 compartment and improve the perchlorate removal capacity of the C2-C5 compartments. Moreover, the high-throughput sequencing analysis showed that bacterial community was significant difference between the HPR and sulfur autotrophic perchlorate removal (SAPR) units. Principal component analysis (PCA) showed that perchlorate removal was more positive correlation with the forward compartments than the posterior compartments of HPR unit. The study confirms that the optimized step-feeding ratio is beneficial to remove the high concentration perchlorate via combining heterotrophic and sulfur autotrophic processes.


Assuntos
Reatores Biológicos , Percloratos , Processos Autotróficos , Desnitrificação , Processos Heterotróficos , Nitratos , Enxofre
16.
Water Res ; 188: 116526, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33125994

RESUMO

The denitrification desulfurization system can be used to remediate wastewater containing carbon, nitrogen, and sulfur. However, the relationship between autotrophic and heterotrophic bacteria remains poorly understood. To better understand the roles and relations of core bacteria, an expanded granular sludge bed (EGSB) reactor was continuously operated under autotrophic (stage I), heterotrophic (stage II) and mixotrophic (stages III-VII) conditions with a 490-day period. Stage IV represented the excellent S0 recovery rate (69.5%). The different trophic conditions caused the obvious succession of dominant bacterial genera. Autotrophic environment (stage I) enriched mostly Thiobacillus, and heterotrophic environment (stage II) was dominated with Azoarcus and Pseudomonas. Thauera, Arcobacter and Azoarcus became the predominant genera under mixotrophic conditions (stage III-VII). Strains belonged to these core genera were further isolated, and all seven isolates were confirmed with denitrifying sulfur oxidation capacity. Heterotrophic strain HDD1 (genus of Thauera) possessed both the highest sulfide degradation and S0 recovery rates. Expression levels of cbbM and gltA genes were positively related with the autotrophic and heterotrophic conditions, respectively. NirK gene was highly expressed between log 3.7-log 4.3 during the entire run. Expression of both sqr and soxB genes were closely related with sulfur conversion. More than 57.5% of S0 recovery rate could be obtained as sqr gene expression was greater than log 3.2, and while, sulfate was the primary form as soxB gene expression higher than log 3.9. The correlation between core microbial genera was very low from network, indicating a complex and non-specific mutualistic network between bacterial functional groups under each nutrient condition, and a stable coexistence state was possibly formed through utilizing each the secondary or waste metabolites in the mixotrophic conditions. This relationship was beneficial to the stability of the microbial community structure in the denitrification desulfurization system.


Assuntos
Reatores Biológicos , Desnitrificação , Processos Autotróficos , Bactérias/genética , Nitratos , Nitrogênio
17.
Bioresour Technol ; 319: 124226, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33049442

RESUMO

Organic carbon can affect nitrogen removal in the anaerobic ammonia oxidation (anammox) process. Two continuous up-flow anaerobic sludge blanket (UASB) reactors were operated under autotrophic (UASBN, without organic carbon) and mixotrophic (UASBCN, with the intermittent addition of acetate and propionate) conditions. Stable operation of anammox systems was achieved, with the nitrogen removal rate and percentage of 2.12 g/(L·d) and 86.4% in UASBN, and 2.09 g/(L·d) and 85.0% in UASBCN, respectively. The network of Candidatus Kuenenia, Thauera, and Nitrosomanas contributed to both nitrogen and carbon metabolisms, and the intermittent addition of acetate and propionate strengthened Ca. Kuenenia's ability to utilize several types of carbon sources. Anammox bacteria showed activity in the presence of organic carbon and without inorganic carbon, confirming the mixotrophic characteristic of Ca. Kuenenia. Cross-feeding of amino acids and vitamins existed among functional microorganisms, with extracellular polymeric substances acting as the media for microbial interactions.


Assuntos
Reatores Biológicos , Carbono , Anaerobiose , Processos Autotróficos , Desnitrificação , Nitrogênio , Oxirredução , Esgotos
18.
Chemosphere ; 263: 127934, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32828055

RESUMO

A high ammonia concentration and chemical oxygen demand (COD) in piggery wastewater force it to be diluted before conventional microalgal treatment to reduce ammonia toxicity. Incomplete treatment of ammonia and COD in piggery wastewater may cause eutrophication, resulting in algal blooms. This study tried to treat raw piggery wastewater without dilution, using three strains of microalgae (Chlorella sorokiniana, Coelastrella sp. and Acutodesmus nygaardii) that outcompeted other algae under heterotrophic, mixotrophic, and autotrophic conditions, respectively, through adaptive evolution at high ammonia concentration. The three stepwise processes were designed to remove (1) small particles, COD, and phosphorus in the 1st heterotrophic C. sorokiniana cultivation, (2) ammonia and COD in the 2nd mixotrophic Coelastrella sp. cultivation, and (3) the remaining ammonia in the 3rd photoautotrophic A. nygaardii cultivation. To enhance ammonia uptake rate, each algal species were inoculated after 2-day nitrogen starvation. When the N-starved three species were inoculated at each step sequentially at 7 g/L for 2 days, the final phosphorus, COD, and ammonia removal efficiencies were 100% (16.4-0 mg/L), 92% (6820-545 mg/L), 90% (850-81 mg/L) and turbidity (99%) after total 6 days.


Assuntos
Adaptação Fisiológica/fisiologia , Amônia/metabolismo , Biodegradação Ambiental , Microalgas/fisiologia , Eliminação de Resíduos Líquidos/métodos , Animais , Processos Autotróficos , Análise da Demanda Biológica de Oxigênio , Biomassa , Chlorella , Processos Heterotróficos , Nitrogênio , Fósforo , Suínos , Águas Residuárias
19.
Bioresour Technol ; 322: 124508, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33341711

RESUMO

Enhanced nitrate removal in the cathode chamber of bioelectrochemical systems (BES) using aerated swine wastewater under high nitrate levels and low organic carbon was investigated in this study, focusing on the relationship between nitrogen and bacterial communities involved in denitrification pathways. BESs with the anion exchange membrane (AEM) under cathodic applied potentials of -0.6 V vs. AgCl/AgCl reference electrode showed a removal rate of 99 ± 2 mg L-1 d-1. Moreover, organic compounds from the untreated full-strength wastewater were simultaneously eliminated in the anode chamber with a removal rate of 0.46 g COD L-1 d-1 with achieved efficiency of 61.4 ± 0.5% from an initial concentration of around 5 g of COD L-1, measured over the course of 7 days. The highest microbial diversity was detected in BESs under potentials of -0.6 V, which include autotrophic denitrifiers such as Syderoxidans, Gallionela and Thiobacillus.


Assuntos
Desnitrificação , Águas Residuárias , Animais , Processos Autotróficos , Reatores Biológicos , Nitratos , Nitrogênio , Suínos
20.
Nat Commun ; 11(1): 5090, 2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037220

RESUMO

Six CO2 fixation pathways are known to operate in photoautotrophic and chemoautotrophic microorganisms. Here, we describe chemolithoautotrophic growth of the sulphate-reducing bacterium Desulfovibrio desulfuricans (strain G11) with hydrogen and sulphate as energy substrates. Genomic, transcriptomic, proteomic and metabolomic analyses reveal that D. desulfuricans assimilates CO2 via the reductive glycine pathway, a seventh CO2 fixation pathway. In this pathway, CO2 is first reduced to formate, which is reduced and condensed with a second CO2 to generate glycine. Glycine is further reduced in D. desulfuricans by glycine reductase to acetyl-P, and then to acetyl-CoA, which is condensed with another CO2 to form pyruvate. Ammonia is involved in the operation of the pathway, which is reflected in the dependence of the autotrophic growth rate on the ammonia concentration. Our study demonstrates microbial autotrophic growth fully supported by this highly ATP-efficient CO2 fixation pathway.


Assuntos
Desulfovibrio desulfuricans/crescimento & desenvolvimento , Desulfovibrio desulfuricans/metabolismo , Glicina/metabolismo , Trifosfato de Adenosina/metabolismo , Amônia/metabolismo , Processos Autotróficos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Dióxido de Carbono/metabolismo , Desulfovibrio desulfuricans/genética , Perfilação da Expressão Gênica , Genoma Bacteriano , Metabolômica
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