Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.199
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Syst Appl Microbiol ; 43(2): 126066, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32019686

RESUMO

On-going studies of phytoplankton-bacterioplankton interactions at the long-term ecological research site Helgoland Roads have indicated that many of the heterotrophic bacterial taxa have not yet been cultivated. A high-throughput approach combining whole cell matrix-assisted laser desorption ionization - time of flight mass spectroscopy with 16S rRNA gene sequencing was applied to the spring bloom of 2016. Aiming at an assessment of cultivability during a spring bloom, cultivation on solid marine media had to be used since dilution to extinction would not have been feasible for a high-throughput approach, as performed in this study. A total of 5023 isolates were obtained from nine weekly samples on eight different solid media between the early-bloom and post-bloom periods. Most of the 4136 strains identified affiliated with Bacteroidetes (13.3%), Gammaproteobacteria (26.9%), Alphaproteobacteria (40.6%) and Actinobacteria (6.7%). Of the 271 operational phylogenetic units (OPUs) identified, 13 are likely to represent novel genera and 143 novel species. A comparison with 16S rRNA gene tag data indicated that most of the isolates were rather rare in surface waters, with the exception of five OPUs affiliating with Rhodobacteraceae, Polaribacter, Psychromonas and Pseudoalteromonas. The effort yielded many novel isolates, yet most of the abundant heterotrophic bacteria still remained elusive. The large strain collection obtained will not only provide insights into the succession of the cultivable fraction of the bacterioplankton, but also enable fine-tuned taxonomic and physiological follow-up studies for improving our knowledge on heterotrophic bacteria in North Sea waters.


Assuntos
Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/metabolismo , Água do Mar/microbiologia , Bactérias/classificação , Bactérias/genética , Meios de Cultura , DNA Bacteriano/genética , Eutrofização , Processos Heterotróficos , Mar do Norte , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , RNA Ribossômico 16S/genética , Estações do Ano , Água do Mar/química , Análise de Sequência de DNA
2.
Bioresour Technol ; 303: 122948, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32058906

RESUMO

A heterotrophic nitrifying and aerobic denitrifying fungus was isolated from lake water and identified as Penicillium tropicum strain IS0293. The strain exhibited efficient heterotrophic nitrification-aerobic denitrification ability and could utilize ammonium, nitrite and nitrate as a sole nitrogen source. Batch tests demonstrated that strain IS0293 can remove nitrate using variety of organic carbon compounds as carbon sources. The effect of woodchip leachate collected at different degradation times on denitrification performance of the strain was also investigated. Furthermore, two denitrifying woodchip bioreactors were constructed to assess the bioaugmention of strain IS0293 for nitrate removal from surface water. Results demonstrated that the incubation of strain IS0293 enhanced the nitrate removal efficiency of the bioreactor. In addition, the average effluent TOC content of the bioaugmention bioreactor was 38.22% lower than the control bioreactor. This study would be valuable to develop an effective technology for nitrate-laden surface water under aerobic conditions.


Assuntos
Processos Heterotróficos , Água , Aerobiose , Reatores Biológicos , Desnitrificação , Fungos , Nitratos , Nitrificação , Nitritos , Nitrogênio
3.
Bioresour Technol ; 302: 122840, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32014729

RESUMO

Herein, a two-stage cultivation process was devised to overcome low pigment content of algal biomass grown in heterotrophy. Post-treatment conditions (i.e., light intensity, temperature, pH and salinity) were initially tested for dense heterotrophically-grown Chlorella sp. HS2 cultures in a multi-channel photobioreactor (mcPBR), and the results clearly indicated the influence of each abiotic factor on algal pigment production. Subsequently, the optimal post-treatment conditions (i.e., 455 µmol m-2 s-1, 34.8℃, pH 8.23 and 0.7% (w/v) salinity), in which highest accumulation of algal pigments is expected, were identified using Response Surface Methodology (RSM). Compared to the control cultures grown in mixotrophy for the same duration of entire two-stage process, the results indicated a significantly higher pigment productivity (i.e., 167.5 mg L-1 day-1) in a 5-L fermenter following the post-treatment at optimal conditions. Collectively, these results suggest that the post-treatment of heterotrophic cultures can be successfully deployed to harness the nascent algae-based bioeconomy.


Assuntos
Chlorella , Processos Heterotróficos , Biomassa , Fotobiorreatores , Salinidade
4.
J Agric Food Chem ; 68(6): 1654-1665, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31935099

RESUMO

Microalgae accumulate bioavailable selenium-containing amino acids (Se-AAs), and these are useful as a food supplement. While this accumulation has been studied in phototrophic algal cultures, little data exists for heterotrophic cultures. We have determined the Se-AAs content, selenium/sulfur (Se/S) substitution rates, and overall Se accumulation balance in photo- and heterotrophic Chlorella cultures. Laboratory trials revealed that heterotrophic cultures tolerate Se doses ∼8-fold higher compared to phototrophic cultures, resulting in a ∼2-3-fold higher Se-AAs content. In large-scale experiments, both cultivation regimes provided comparable Se-AAs content. Outdoor phototrophic cultures accumulated up to 400 µg g-1 of total Se-AAs and exhibited a high level of Se/S substitution (5-10%) with 30-60% organic/total Se embedded in the biomass. A slightly higher content of Se-AAs and ratio of Se/S substitution was obtained for a heterotrophic culture in pilot-scale fermentors. The data presented here shows that heterotrophic Chlorella cultures provide an alternative for Se-enriched biomass production and provides information on Se-AAs content and speciation in different cultivation regimes.


Assuntos
Aminoácidos/metabolismo , Chlorella/metabolismo , Chlorella/efeitos da radiação , Selênio/metabolismo , Aminoácidos/análise , Biomassa , Chlorella/classificação , Chlorella/crescimento & desenvolvimento , Processos Heterotróficos , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Microalgas/efeitos da radiação , Processos Fototróficos , Selênio/análise
5.
Bioresour Technol ; 301: 122726, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31927458

RESUMO

High salinity and high organic concentration impose negative impacts on autotrophic nitrification, which hinders efficient nitrogen removal. To achieve efficient nitrogen removal, high saline wastewater nitrogen removal systems with different COD/TN ratios based on heterotrophic nitrification-aerobic denitrification (HN-AD) process were established in this study. Results demonstrated that the COD/TN ratio had significant effects on nitrogen removal efficiency, microbial community structures and metabolic pathways. The optimal COD/TN ratio was 25 for nitrogen removal, with NH4+-N and TN removal rates of 11.86 mg·L-1·h-1 and 11.50 mg·L-1·h-1, respectively (3.65 and 3.31 times higher than those COD/TN ratio of 10). 16S rRNA high-throughput sequencing revealed that HN-AD functional bacteria (Pseudomonas, Bacillus, Paracoccus) with highest abundance (7.61%) played a key role in high saline wastewater treatment. And Halomonas, Nitrincola and Oceanimonas participated in the denitrification process. Moreover, the abundance of genes related to nitrogen removal was the highest (1.90%) revealed by functional genes prediction.


Assuntos
Microbiota , Nitrificação , Reatores Biológicos , Desnitrificação , Processos Heterotróficos , Nitrogênio , RNA Ribossômico 16S , Águas Residuárias
6.
Water Res ; 171: 115457, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31931377

RESUMO

Although estimates of total CO2 emissions from global estuaries are gradually decreasing, current numbers are based on limited data and the impacts of anthropogenic and seasonal disturbances have not been studied extensively. Our study estimates annual and seasonal CO2 fluxes in China's Yellow River Estuary (YRE) which incorporated spatiotemporal variations and the effects of water and sediment regulation (WSR). Aquatic metabolism was estimated using Odum's open water dissolved oxygen methods and used to represent the production and assimilation of CO2. Net ecosystem production (NEP) was used to represent the CO2 flux from biological activities and estimate the major CO2 emitters in the YRE. According to our measurements, the annual CO2 release was 6.14 ± 33.63 mol C m-2 yr-1 from 2009 to 2013 and the annual CO2 efflux from the 1521.3 km2 of estuarine surface area was 0.11 ± 0.61 Tg C yr-1 in the YRE. High CO2 emissions in autumn were balanced by high CO2 sequestration in summer, leading to a lower than expected annual net CO2 efflux. The system is an atmospheric CO2 source in spring and winter, near neutral in early summer, a large sink in late summer after WSR, and finally a large atmospheric CO2 source in autumn. Discharge events and seasonality jointly affect estuarine CO2 flux. High CO2 sequestration in summer is due mainly to a combination of high water temperature, chlorophyll a levels, dissolved inorganic carbon, and solar radiation and low turbidity, discharge, and chemical oxygen demand (COD) after WSR. WSR supports the high gross primary productivity rate which exceeds the increase in ecosystem respiration. Although the YRE, as a whole, is a source of atmospheric CO2, the amount of CO2 released is lower than the average estuarine value of mid-latitude regions. Our findings therefore suggest that global CO2 release from estuarine systems is overestimated if spatiotemporal variations and the effects of anthropogenic disturbance are excluded. The NEP method is effective for estimating the CO2 flux, especially in estuaries where CO2 variation is mainly due to biological processes.


Assuntos
Estuários , Rios , Dióxido de Carbono , China , Clorofila A , Ecossistema , Monitoramento Ambiental , Processos Heterotróficos , Estações do Ano
7.
Bioresour Technol ; 301: 122749, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31951959

RESUMO

A novel strain was isolated from municipal activated sludge and identified as Acinetobacter sp. ND7 based on its phenotypic and phylogenetic characteristics, which had efficient capability for heterotrophic nitrification and aerobic denitrification. Strain ND7 could remove approximately 99.8% of ammonium-N (51.0 mg/L), 96.2% of nitrite-N (51.8 mg/L) and 97.18% of nitrate-N (52.1 mg/L), with the maximum specific removal rate of 5.74, 4.17 and 3.63 mg/(L h), respectively. Ammonium was manifested to be utilized preferentially during simultaneous nitrification and denitrification. The functional genes hao, napA and nirS were successfully amplified by PCR, further evidencing the heterotrophic nitrification and aerobic denitrification capability of Acinetobacter sp. ND7. The optimal conditions for nitrogen removal were temperature of 35 °C, C/N ratio of 8. Acinetobacter sp. ND7 displays superior performance for nitrogen removal, with no nitrite accumulation under aerobic condition, and thus has significant potential for practical application for nitrogen removal from wastewater.


Assuntos
Acinetobacter , Compostos de Amônio , Aerobiose , Desnitrificação , Processos Heterotróficos , Nitrificação , Nitritos , Nitrogênio , Filogenia , Esgotos
8.
Waste Manag ; 102: 198-203, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31678806

RESUMO

An estimation of the economy of Hermetia illucens and Chlorella pyrenoidosa cultivations as food waste treatment with benefits was carried out. For both organisms, a process scale was assumed to treat 56.3 t of wet food waste per day, which is equivalent to the amount of food waste appearing in a catchment area of 141,000 inhabitants. Using hypothetical insect and heterotrophic microalgae cultivation processes, a daily production of 3.64 t and 7.14 t dried biomass, respectively, can be achieved. For the cultivation of H. illucens, equipment and daily operational costs were estimated at 79,358.15 € and 5,281.56 €, respectively. Equipment and operational costs for the C. pyrenoidosa cultivation was 50 and 6 times higher, respectively. The higher costs reflect the more complex and advanced process compared to H. illucens cultivation. The internal return rate for a plant lifetime of 20 times revealed an economic benefit when C. pyrenoidosa biomass is produced. Nevertheless, both processes were found economically feasible when dried biomass is directly commercialized as food without any further downstream processing. However, extraction and purification of special chemicals, such as unsaturated fatty acids and pigments, can significantly increase the revenue.


Assuntos
Chlorella , Microalgas , Eliminação de Resíduos , Animais , Biomassa , Alimentos , Processos Heterotróficos , Insetos , Águas Residuárias
9.
Aquat Toxicol ; 218: 105360, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31765943

RESUMO

Labile dissolved organic carbon (DOC) is a major pollutant in coastal marine environments affected by anthropogenic impacts, and may significantly contribute to coral bleaching and subsequent mortality on coastal reefs. DOC can cause bleaching indirectly through the rapid proliferation of copiotrophic and pathogenic bacteria. Here we demonstrate that labile DOC compounds can also impair the coral-dinoflagellate symbiosis by directly affecting coral physiology on both the host and algal symbiont level. In a controlled aquarium experiment, we monitored over several weeks key physiological parameters of the tropical coral Stylophora pistillata exposed to ambient and elevated labile DOC levels (0.1 and 1.0 mM) in combination with low and high nitrogen (i.e. ammonium) conditions (0.2 and 4.0 µM). At the symbiont level, DOC exposure under low ammonium availability decreased the photosynthetic efficiency accompanied by ∼75 % Chl a and ∼50 % symbiont cell reduction. The photosynthetic functioning of the symbionts recovered once the DOC enrichment ceased indicating a reversible shift between autotrophic and heterotrophic metabolism. At the host level, the assimilation of exogenous DOC sustained the tissue carbon reserves, but induced a depletion of the nitrogen reserves, indicated by ∼35 % decreased protein levels. This suggests an imbalanced exogenous carbon to nitrogen supply with nitrogen potentially limiting host metabolism on the long-term. We also demonstrate that increased ammonium availability delayed DOC-induced bleaching likely by keeping symbionts in a photosynthetically competent state, which is crucial for symbiosis maintenance and coral survival. Overall, the present study provides further insights into how coastal pollution can de-stabilize the coral-algal symbiosis and cause coral bleaching. Therefore, reducing coastal pollution and sustaining ecological integrity are critical to strengthen the resilience of coral reefs facing climate change.


Assuntos
Compostos de Amônio/farmacologia , Antozoários/efeitos dos fármacos , Dinoflagelados/efeitos dos fármacos , Compostos Orgânicos/toxicidade , Simbiose/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antozoários/metabolismo , Processos Autotróficos , Mudança Climática , Recifes de Corais , Dinoflagelados/metabolismo , Processos Heterotróficos , Oceano Índico , Fotossíntese/efeitos dos fármacos
10.
J Sci Food Agric ; 100(3): 1344-1349, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31605384

RESUMO

BACKGROUND: Water-soluble proteins extracted from the heterotrophically cultivated microalga Chlorella protothecoides have been shown to have a good solubility over a broad pH range, which makes them a promising candidate for beverage formulations. This study investigated the sensory properties of dispersions of a protein-rich extract from C. protothecoides at neutral and pH 3. RESULTS: Sensory acceptance tests of the pure extract revealed an overall low acceptance at pH 7 without sucrose addition. Sensory acceptance was significantly (P ≤ 0.05) increased by lowering the pH to 3 with citric acid, and the addition of 50 g kg-1 sucrose. Here, overall positive sensory acceptance ratings were achieved up to a protein extract concentration of 40 g kg-1 . Basic taste evaluations showed only low bitterness scores and no significant (P > 0.05) increase in bitterness with decreasing pH. CONCLUSION: It is suggested that protein-rich extracts from C. protothecoides have promising sensory properties in beverage formulations. © 2019 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Chlorella/química , Extratos Vegetais/química , Proteínas de Plantas/química , Bebidas/análise , Chlorella/crescimento & desenvolvimento , Processos Heterotróficos , Humanos , Concentração de Íons de Hidrogênio , Microalgas/química , Microalgas/crescimento & desenvolvimento , Extratos Vegetais/isolamento & purificação , Proteínas de Plantas/isolamento & purificação , Solubilidade , Paladar
11.
Chemosphere ; 241: 124993, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31600622

RESUMO

Azoles are emerging contaminants that are resistant to biodegradation during wastewater treatment. Their presence has been widely reported in wastewater effluents and receiving waters. In this work, the potential inhibition of nitrification process by six different azole compounds in wastewater treatment plants was investigated in batch bioassays. The azoles studied included three diazoles: pyrazole (Pz); 1-methylpyrazole (MePz); 3,5-dimethylpyrazole (DMePz); and three triazoles: 1,2,4-triazole (Tz); benzotriazole (BTz); and 5-methyl benzotriazole (MeBTz). The concentration of azoles causing 50% inhibition (IC50) increased (azoles became less inhibitory) in the following order (mg L-1): BTz (1.99) < MeBTz (2.18) < Pz (2.69) < Tz (3.53) < DMePz (17.3) < MePz (49.6). No clear structure-inhibitory relationships were found using Log P and pKa as structural properties. The toxicity of any given azole may be related to the role of substituent groups on disabling/enabling binding to the active sites of metallo-enzymes in nitrifying microorganisms. This is exemplified by the low toxicity of MePz, which has a cyclic N blocked by a methyl group. The observed inhibition caused to nitrifying bacteria is more severe than their cytotoxicity to other target organisms (e.g., methanogens and heterotrophic bacteria), suggesting a specific inhibition to the copper-containing enzyme, ammonium monooxygenase, in ammonia oxidizing nitrifying microorganisms.


Assuntos
Azóis/farmacologia , Biodegradação Ambiental , Nitrificação/efeitos dos fármacos , Esgotos/microbiologia , Compostos de Amônio/metabolismo , Azóis/química , Azóis/toxicidade , Bactérias/metabolismo , Processos Heterotróficos , Triazóis/farmacologia , Águas Residuárias/química
12.
Environ Technol ; 41(6): 719-729, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30092717

RESUMO

Growth studies are important to increase the knowledge about the physiology of microalgae. The development of suitable culture media allows optimum growth to each species. The genus Chlorella has the ability to adapt to various environmental and nutritional conditions. Thus, the aim of this work was to evaluate the physiology of Chlorella sorokiniana CTT 7727 at different growth conditions with Basal Bold (BB) medium. For that, heterotrophic, autotrophic and mixotrophic cultures were carried out. The maximum specific growth rates (µmax), the maximum biomass concentrations (Xmax) and cell productivities (PX) were calculated for each experiment. Among all the treatments evaluated, that with 24 h light, 3x BB (g L-1) and CO2 presented a higher µmax (0.40 day-1) and maximum cell concentration due the increased concentration of nutrients. Replacement of dark to light has increased Xmax from 2.3 × 105 to 9.3 × 106 cells mL-1 in regular BB medium and 3.6 × 105 to 2.1 × 107 cells mL-1 in 3x BB medium in autotrophic cultivations. The PX increased from 2.4 × 104 cells mL-1 h-1 (1x BB (g L-1)) to 3.6 × 104 cells mL-1 h-1 (3x BB (g L-1)), in the presence of 24 light and CO2. However, the same behaviour was not observed when BB concentration was increased 6, 8 or 10 times the initial concentration of BB medium. Experiments with pulses of concentrated nutrients showed that declining cells can resume their growth after nutrient depletion, but the viability is decreased after successive pulses.


Assuntos
Chlorella , Microalgas , Biomassa , Carbono , Processos Heterotróficos , Sais
13.
Chemosphere ; 239: 124800, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526993

RESUMO

Biological degradation of high strength phenol and its derivatives in groundwater is problematic because these compounds are toxic to human and microbes. To evaluate the feasibility of in situ bioremediation using sequential aerobic respiration and heterotrophic denitrification, a field single-well-drift test (SWDT) was conducted in groundwater contaminated with coal tar distillates. To stimulate indigenous phenol degrading microorganisms, a 1400 L of oxygen-saturated test solution containing bromide (3.96 ±â€¯0.179 mmol-Br/L) and nitrate (5.34 ±â€¯0.187 mmol NO3--N/L) was injected into an aquifer. After injection of the test solution, significant consumption of dissolved oxygen (DO) was immediately observed; then, degradation of the methyl derivatives o-cresol and m,p-cresol was observed with average zero-order rate coefficients of 0.047 mmol/L/d and 0.23 mmol/L/d, respectively. After 73% of the injected DO was consumed, significant NO3- consumption was observed along with degradation of phenol and the dimethyl derivatives 2,4-xylenol and 3,5-xylenol, which had average zero-order rate coefficients of 0.17 mmol/L/d, 0.060 mmol/L/d, and 0.018 mmol/L/d, respectively. The production of CO2, NO2-, and N2O along with significant consumption of DO and NO3- suggest that phenolic compounds were biologically degraded by sequential aerobic respiration and heterotrophic denitrification. The results of 16s RNA analysis revealed that, after injection of the test solution, a bacterium that shared a 99% 16s rRNA sequence similarity with an uncultured bacterium revealed to be Pseudomonas stutzeri, a facultative heterotrophic denitrifier, was found in the aquifer. Thus, these results suggest that simultaneous injection of DO and NO3- is an appropriate in situ bioremediation strategy for degrading mixtures of high-strength phenolic compounds in an aquifer.


Assuntos
Água Subterrânea/microbiologia , Fenóis/metabolismo , Poluentes Químicos da Água/metabolismo , Aerobiose , Biodegradação Ambiental , Brometos/metabolismo , Cresóis/química , Cresóis/metabolismo , Desnitrificação , Estudos de Viabilidade , Água Subterrânea/química , Processos Heterotróficos , Humanos , Nitratos/metabolismo , Nitrogênio/metabolismo , Fenóis/química , Pseudomonas stutzeri/genética , Pseudomonas stutzeri/metabolismo , RNA Ribossômico 16S/metabolismo , República da Coreia , Poluentes Químicos da Água/química , Xilenos/química , Xilenos/metabolismo
14.
Chemosphere ; 239: 124726, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494322

RESUMO

A novel start-up strategy for sulfur-based mixotrophic denitrification biofilters (mDNBFs) by rhamnolipid was investigated for the first time. Rhamnolipid with gradient concentrations (0-120 mg/L) was added into five lab-scale mDNBFs. Results showed that rhamnolipid could promote biomass yield and nitrogen removal rate (NRR) by 71.7% and 68.7%, respectively, while its effect on EPS and adhesion force was concentration-dependent. The spatial distribution characteristics of microbial communities demonstrated the enrichment of main heterotrophic denitrifying bacteria outcompeted that of the autotrophs, with a more pronounced difference in high concentration rhamnolipid-treated mDNBFs. Furthermore, highest abundance of napA, narG, nirK and nosZ genes was observed in 80 mg/L rhamnolipid-treated mDNBF. Interfacial processes including solubilizing effect and hydration repulse and variations of organics were discussed to explicate the underlying mechanism. The study enlightened that an appropriate concentration (∼80 mg/L) of rhamnolipid may be a good solution for accelerating biofilm formation and enriching denitrifying bacteria to promote denitrification performance of mDNBFs treating low C/N wastewater.


Assuntos
Glicolipídeos/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Bactérias/genética , Bactérias/metabolismo , Carbono/metabolismo , Desnitrificação , Genes Bacterianos , Processos Heterotróficos , Microbiota , Nitrogênio/metabolismo , Enxofre/metabolismo , Eliminação de Resíduos Líquidos/instrumentação
15.
Huan Jing Ke Xue ; 40(8): 3713-3721, 2019 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854780

RESUMO

Due to the problems of traditional biological nitrogen and phosphorus removal, including long process duration and high infrastructural and operational costs, the simultaneous nitrogen and phosphorus removal capabilities, influencing factors and kinetic characteristics were systematically studied using the heterotrophic nitrifier Acinetobacter junii NP1 which possesses efficient simultaneous nitrogen and phosphorus removal ability. The results showed that strain NP1 exhibited efficient heterotrophic nitrification ability with a maximum ammonia removal rate of 99.12%. Furthermore, only small amounts of nitrification intermediates were accumulated during the reaction process. Strain NP1 also adapted well to higher ammonia nitrogen loading. In addition, strain NP1 had efficient aerobic denitrification characteristics, and could utilize nitrite and nitrate for growth and metabolism, achieving a maximum removal rate of 91.40% and 95.10%, respectively. The heterotrophic nitrification process of strain NP1 was accompanied by simultaneous phosphorus accumulation, and the appropriate ratio of nitrogen to phosphorus was beneficial for the simultaneous removal of nitrogen and phosphorus. When the ratio of nitrogen to phosphorus was 5:1, the maximum ammonia nitrogen and phosphate removal rates reached 99.21% and 88.35%, respectively. The bacterial growth process of stain NP1 matched the Logistic model (R2>0.99), and the nitrogen and phosphate degradation conformed to the Compertz model (R2>0.99). The maximum conversion rates of nitrogen and phosphate (Rm) obtained by model fitting were in the order ammonia>nitrate>nitrite, and lag time (t0) was in the order nitrate>nitrite>ammonia. According to the analysis of the degradation kinetics of the matrix and the removal rate of nitrogen and phosphorus, the optimal conditions were found to be sodium succinate, C/N=10, T=30℃, and r=160 r·min-1.


Assuntos
Acinetobacter , Nitrogênio , Fósforo , Purificação da Água , Acinetobacter/metabolismo , Aerobiose , Desnitrificação , Processos Heterotróficos , Cinética , Nitrificação , Nitritos
16.
Huan Jing Ke Xue ; 40(9): 4128-4135, 2019 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854877

RESUMO

The integrated autotrophic and heterotrophic denitrification (IAHD) process, which can simultaneously degrade sulfide, nitrate, and organic carbon with nitrate as a solo electron acceptor, has gained increasing attention as a key unit in industrial wastewater treatment. Micro-aerobic technology, which introduces trace oxygen as an additional electron acceptor, has been demonstrated as an effective strategy for enhancing the IAHD performance. This study focus on the electronic balance calculation of the IAHD process and reveals for the first time that the IAHD process can efficient proceed with an insufficient supply of electron acceptors (nitrate) under micro-aerobic conditions. In the IAHD batch tests, the highest sulfide, nitrate, and acetate removal efficiencies and rates were obtained with an electronic deletion rate peak at 55.1%. Further sulfide oxidizing batch tests demonstrated that the electronic deletion rates were 18.7% and 38.2% under oxygen contents of 5 mL and 10 mL, respectively, in the biological sulfide oxidizing process. Illumina sequencing was used to analyze the microbial community structure in the sulfide oxidation process and indicated Thiobacillus, Thauera, Mangroviflexus, and Erysipelothrix dominated in all community compositions, in which the relative abundance of Thiobacillus increased with an increase in the electronic deletion rate. This study reveals a potential linkage between the electronic gap and the enhanced IAHD performance, which proves new insights into the simultaneous sulfur, nitrogen, and organic carbon removal process.


Assuntos
Desnitrificação , Elétrons , Processos Autotróficos , Reatores Biológicos , Processos Heterotróficos , Nitratos
17.
Water Sci Technol ; 80(5): 892-901, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31746796

RESUMO

Characteristics of Chlorella sorokiniana treating wastewater with consideration of HRT (6 d, 16 h, 8 h), hydraulic conditions, light or dark culture were evaluated and compared with activated sludge. Results showed that optimal HRT was 8 h; if longer, effluent chemical oxygen demand (COD) and NH4+-N in the dark began to rebound. Mixing was beneficial to COD removal of algae, while aeration was suitable for nutrient removal. Growth of C. sorokiniana in the light was mixotrophic growth and 1.3-1.7 times more than that of dark heterotrophic growth. The maximum specific growth rate (µmax), productivity, and biomass yields on COD (YCOD), N (YNH4), P (YP) of algae were higher in the light than that in the dark. COD assimilation capacity of algae was similar to activated sludge but with different dynamics. N and P assimilation capacity of algae was 1.4, 1.2-2.5 times more than activated sludge; N and P removal efficiency of algae was 5%-10%, 10%-55% respectively higher than activated sludge. This study confirmed the advantage of algae over activated sludge and reveal why algae could assist the activated sludge process.


Assuntos
Chlorella , Águas Residuárias , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Processos Heterotróficos , Esgotos , Eliminação de Resíduos Líquidos
18.
J Basic Microbiol ; 59(12): 1208-1216, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31613006

RESUMO

The current research focuses on anaerobic respiration of arsenic and other toxic metals by purple nonsulfur bacteria (PNSB). Among the optimization assays performed were carbon utilization, cross metal resistance, and metal respiration, along with a comparison of each assay in photoheterotrophic and chemoheterotrophic growth. The bacteria were identified by the classification of 16S ribosomal RNA gene sequences. Rhodobacter sp. PI3 proved to be more versatile in carbon source utilization (acetate, lactate, citrate, and oxalate), whereas Rhodopseudomonas palustris PI5 proved to be more versatile in metal resistance (arsenate, arsenite, cobalt, lead, selenium, and nickel). Both the strains were found to be positive for photofermentative hydrogen production along with arsenic respiration. This study reveals that anaerobic conditions are more appropriate for better efficiency of PNSB. Our study demonstrates that R. palustris PI5 and Rhodobacter sp. PI3 can be promising candidates for the biohydrogen production along with metal detoxification using heavy metal-polluted effluents as a substrate.


Assuntos
Arsênico/metabolismo , Hidrogênio/metabolismo , Metais/metabolismo , Rhodobacter/metabolismo , Rodopseudomonas/metabolismo , Anaerobiose , Biodegradação Ambiental , Carbono/metabolismo , DNA Bacteriano/genética , Processos Heterotróficos , Filogenia , Pigmentos Biológicos/metabolismo , RNA Ribossômico 16S/genética , Rhodobacter/classificação , Rhodobacter/genética , Rodopseudomonas/classificação , Rodopseudomonas/genética , Análise de Sequência de DNA , Microbiologia da Água
19.
Bioresour Technol ; 294: 122114, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31520854

RESUMO

A novel strain DQ01 capable of simultaneous removal of nitrate and ammonium under the aerobic condition was isolated from the landfill leachate and identified as Stenotrophomonas maltophilia. The result showed that S. maltophilia had carbon selection for the nitrogen removal pathway, and preferred to utilize carboxylate rather than carbohydrate, as carboxylate could directly participate in TCA cycle without Embden Meyerhof Parmas (EMP). Nitrogen and carbon balances confirmed that the ammonium assimilation was the main or even sole removal pathway for S. maltophilia, and carboxylate was more conducive to heterotrophic nitrification-aerobic denitrification (HN-AD) process due to the serious self-alkalization and higher reduction potential of carboxylate, which followed: NH4+ → NO2- → NO3- → NO2- → NO due to the lack of nor and nos. Meanwhile, the higher C/N and nitrate could generate a more powerful ion transport driving force to accelerate the electron transfer in the denitrifying respiratory chain.


Assuntos
Nitrogênio , Stenotrophomonas maltophilia , Aerobiose , Carbono , Desnitrificação , Elétrons , Processos Heterotróficos , Nitrificação , Nitritos
20.
Sci Total Environ ; 697: 134047, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31491641

RESUMO

In this study, simultaneous nitrification and denitrification (SND) process was successfully established in a hybrid sequencing batch biofilm reactor (HSBBR). High removal efficiency of NH4+-N (98.0±2.4% to 99.8±0.4%) and COD (86.6±4.0% to 91.6±1.8%) was observed in the salinity range of 0.0 to 2.4%. SND via nitrite, replacing SND via nitrate, became the main nitrogen removal pathway at 1.6% and 2.4% salinity. Suspended sludge and biofilm shared similar microbial composition. Dominant genera were substituted by salt-adaptable microbes as salinity increasing. Abundance of autotrophic ammonia-oxidizing bacteria (Nitrosomonas) increased with elevated salinity, while autotrophic nitrite-oxidizing bacteria (Nitrospira) exhibited extreme sensitivity to salinity. The presence of Gemmata demonstrated that heterotrophic nitrification co-existed with autotrophic nitrification in the SND process. Aerobic denitrifiers (Denitratisoma and Thauera) were also identified. Thiothrix, Sedimenticola, Sulfuritalea, Arcobacter (sulfide-based autotrophic denitrifier) and Hydrogenophaga (hydrogen-based autotrophic denitrifier) were detected in both S-sludge and biofilm. The occurrence of ANAMMOX bacteria Pirellula and Planctomyces indicated that ANAMMOX process was another pathway for nitrogen removal. Nitrogen removal in the HSBBR was accomplished via diverse pathways, including traditional autotrophic nitrification/heterotrophic denitrification, heterotrophic nitrification, aerobic and autotrophic denitrification, and ANAMMOX.


Assuntos
Reatores Biológicos , Nitrogênio/metabolismo , Salinidade , Eliminação de Resíduos Líquidos , Águas Residuárias/microbiologia , Microbiologia da Água , Processos Autotróficos , Bactérias , Biofilmes , Desnitrificação , Processos Heterotróficos , Microbiota , Nitrificação , Esgotos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA