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1.
Chemosphere ; 244: 125513, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050330

RESUMO

To achieve efficient biological nutrients removal at low temperature, a modified sequencing batch reactor (SBR) was developed at 10 °C by extending sludge retention time (SRT), shortening aerobic stage and compensating anoxic stage. The average removal rates of ammonium (NH4+-N), total nitrogen (TN) and total phosphorus (TP) were 98.82%, 94.12% and 96.04%, respectively. Variation of carbon source in a typical cycle demonstrated the maximum synthesis of poly-ß-hydroxybutyrate (PHB) (60 mg/L) occurred after feast period. Furthermore, the TP in sludge reached 50.4 mg/g mixed liquor suspended solids (MLSS) (78.4% was inorganic phosphorus and 21.6% was organic phosphorus) after 120 days of operation, indicating an excellent P-accumulating capacity was achieved in this system. Ammonia oxidizing bacteria (AOB) activity inhibition test verified both AOB and ammonia oxidizing archaea (AOA) were involved in ammonia-oxidizing process and the latter accounted for 17%-19%. Metagenomic-based taxonomy revealed the dominant genera were Candidatus Accumulibacter (12.18%), Dechloromonas (7.54%), Haliangium (6.69%) and Candidatus Contendobacter (3.40%). As described from the denitrifying genes perspective, with the exception of nitrite reduction (performed by denitrifiers), denitrifying phosphorus-accumulating organisms (DPAOs) played a leading role in denitrification pathway, showing that poly-ß-hydroxyalkanoates (PHA)-driven nutrients removal was the dominate process.


Assuntos
Reatores Biológicos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Amônia/metabolismo , Compostos de Amônio , Betaproteobacteria/metabolismo , Carbono/metabolismo , Temperatura Baixa , Desnitrificação , Hidroxibutiratos , Metagenoma , Microbiota , Nitritos/metabolismo , Nitrogênio/análise , Nitrogênio/metabolismo , Fósforo/análise , Fósforo/metabolismo , Poliésteres , Esgotos/química , Temperatura Ambiente , Poluentes da Água/análise , Poluentes da Água/metabolismo
2.
Microbes Environ ; 35(1)2020.
Artigo em Inglês | MEDLINE | ID: mdl-32009017

RESUMO

The maximum ammonia oxidation potential (AOP) of a topsoil in Langhovde, East Antarctica was 22.1±2.4| |ng N g-1 dry soil h-1 (2| |mM ammonium, 10°C, n=3). This topsoil exhibited twin AOP peaks (1 and 2| |mM ammonium) at 10°C, but not at 20°C. Six and ten operational taxonomic units (OTUs) were identified for ammonia-oxidizing bacteria (AOB) and archaea (AOA) amoA, respectively. AOB were classified into Nitrosospira; the two dominant OTUs corresponded to the Mount Everest cluster. AOA were classified into three clusters; Nitrososphaera and Nitrosocosmicus were the two dominant clusters.


Assuntos
Amônia/metabolismo , Briófitas/microbiologia , Líquens/microbiologia , Microbiologia do Solo , Regiões Antárticas , Archaea/classificação , Archaea/genética , Archaea/isolamento & purificação , Archaea/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Nitrificação , Oxirredução , Filogenia , Solo/química , Temperatura Ambiente
3.
Chemosphere ; 243: 125399, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995869

RESUMO

Nutrient removal efficiency in green sorption media such as biosorption activated media (BAM) for treating stormwater runoff can be heavily influenced either on a short- or long-term basis by varying field conditions of linear ditches due to the presence of copper in stormwater runoff. It is also noticeable that the linear ditch undergoes physical or mechanical impacts from the traffic compaction, chemical impact of carbon sources from the nearby farmland, and biological impact from potential animal activities (such as gopher tortoises, moles, and ants). In the nitrogen cycle, two denitrification pathways, the dissimilatory nitrate reduction to ammonia and common denitrification, are deemed critical for such assessment. A fixed-bed column study was set up to mimic different linear ditch field conditions for BAM applications and measure the effect of short-and long-term copper addition on microbial dynamics given the varying decomposition of dissolved organic nitrogen (DON). The findings confirm that, as the denitrifiers (in the second pathway) were the dominant species, their population continued to grow and maintain small-sized cells for extracellular sequestration under long-term copper impact. Furthermore, the study indicated that the ammonia oxidizer comammox was found in higher quantities than ammonia oxidizing bacteria or archaea. An enormous amount of DON was released during this process to bind the copper ion and reduce its toxicity as the enzymatic cascade effect appeared. In addition, the long-term copper exposure posed salient inhibitory effects on the microbial community regardless of varying field conditions in BAM. Short-term copper toxicity exerted an important but varying role in the enzymatic cascade effect over different linear ditch field conditions in BAM.


Assuntos
Cobre/química , Enzimas/metabolismo , Nitrogênio/isolamento & purificação , Purificação da Água/métodos , Amônia/metabolismo , Carbono , Cobre/metabolismo , Desnitrificação , Enzimas/química , Consórcios Microbianos/efeitos dos fármacos , Nitratos/metabolismo
4.
J Sci Food Agric ; 100(4): 1608-1615, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31773732

RESUMO

BACKGROUND: The possible escape from the rumen of undegraded-feed soluble proteins (SP) was investigated using nitrogen-15 (15 N) infusions (25 mg) in three rumen and duodenum cannulated wethers. Animals were fed three isoproteic diets differing in SP content and including protein concentrates either untreated (control) or treated with solutions of either malic acid (MHT) or orthophosphoric acid (OHT) and heat. RESULTS: Compared with control, MHT and OHT diets reduced ruminal concentrations of ammonia-nitrogen (NH3 -N) by 35.9% (P = 0.007), non-ammonia nitrogen (NAN) by 36.8% (P = 0.007), and SP-nitrogen (SP-N) by 45.2% (P = 0.072) over the post-feeding period. Both NAN and SP-N were lower (P ≤ 0.040) for OHT than for MHT diet. The 15 N enrichment of NAN and SP-N did not vary either among diets or with time, and both values were closely related (R2 = 0.965; P < 0.001). Estimations, either using solid-associated bacteria (SAB) or liquid-associated bacteria (LAB) as a reference, indicated that 0.983 and 0.894 of SP-N (values averaged across diets) was of microbial origin, respectively, which would indicate a practically negligible ruminal escape of feed SP-N. Values of 15 N-enrichment in SAB and LAB fitted well to previously published SAB-LAB relationships, indicating a 22% underevaluation of the N supply from SAB when only LAB is used as a reference. CONCLUSION: Both the negligible ruminal escape of feed SP and the underevaluation of the bacterial nutrient supply as a consequence of the use of LAB as the only bacterial reference should be considered to improve ruminant protein feeding systems. © 2019 Society of Chemical Industry.


Assuntos
Bactérias/metabolismo , Proteínas/metabolismo , Rúmen/microbiologia , Amônia/análise , Amônia/metabolismo , Ração Animal/análise , Animais , Bactérias/classificação , Bactérias/isolamento & purificação , Duodeno/metabolismo , Duodeno/microbiologia , Masculino , Isótopos de Nitrogênio/análise , Isótopos de Nitrogênio/metabolismo , Nutrientes/análise , Nutrientes/metabolismo , Proteínas/análise , Rúmen/metabolismo
5.
Theriogenology ; 141: 82-90, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31518732

RESUMO

Relative to alanine and serine amino acid levels, glutamine is highly abundant in follicular fluid, and is an important source of energy required for oocyte maturation and embryo development. Thus, glutamine is an essential component of in vitro embryo culture media. However, glutamine has poor stability and degrades spontaneously in solution to form ammonia and pyrrolidonecarboxylic acid. In the present study, we aimed to explore the effect of substituting l-glutamine with glycine-glutamine, a more stable glutamine, on development of early parthenogenetic embryos and in vitro fertilization (IVF) embryos in bovine. Results revealed that glycine-glutamine can significantly increase cleavage rate (parthenogenetic embryos:87.24% vs. 72.61%, IVF embryos:89.33% vs. 83.79%, P < 0.01), blastocyst number (parthenogenetic embryos:24.98% vs. 18.07%, IVF embryos:33.53% vs. 27.29%, P < 0.01), and blastocyst number (parthenogenetic embryos:96 vs. 76, IVF embryos:114 vs. 109, P < 0.01), reduce blastocyst apoptosis (parthenogenetic embryos:3.72% vs. 6.65%, IVF embryos:2.53% vs.6.23%, P < 0.01), alleviate embryo ammonia toxicity, and reduce the content of reactive oxygen species (ROS) compared with the l-glutamine. In addition, glycine-glutamine can alter epigenetic reprogramming by increasing the expression of HDAC1 (Histone Deacetylase 1) and decreasing the relative expression levels of H3K9 acetylation in early parthenogenetic embryos and IVF embryos. From our present study, we concluded that glycine-glutamine is an effective substitute of glutamine in modified synthetic oviduct fluid with amino acids (mSOFaa).


Assuntos
Bovinos/embriologia , Técnicas de Cultura Embrionária/veterinária , Fertilização In Vitro/veterinária , Glutamina/química , Glicina/química , Partenogênese/fisiologia , Acetilação , Amônia/metabolismo , Animais , Apoptose , Meios de Cultura , Dipeptídeos/química , Dipeptídeos/farmacologia , Glutamina/farmacologia , Glicina/farmacologia , Histonas/metabolismo , Espécies Reativas de Oxigênio
6.
J Dairy Sci ; 103(1): 396-409, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31733854

RESUMO

The aim of this study was to determine the effects of pretreatment with reducing sugars or with an enzymatic cocktail before extrusion of fava bean on intake, milk yield and composition, N partitioning, and plasma and ruminal parameters. The main hypothesis was that these pretreatment conditions would allow better N protection in the rumen compared with classic pretreatment before extrusion, thanks to an increase of sugar proportion, either exogenous or endogenous with enzymatic actions. Sixteen Holstein cows were used in a 4 × 4 Latin square design experiment. Cow were fed a diet with a 56:44 forage to concentrate ratio and containing 16.2% of crude protein (CP; dry matter basis). Concentrate consisted of fava bean:linseed blends (90:10%, raw basis) distributed either raw, extruded after pretreatment without additive, extruded after pretreatment with reducing sugars, or extruded after pretreatment with an enzymatic cocktail. The experimental blends provided 53% of total CP in the diet. Intake, milk yield and composition, ruminal pH, volatile fatty acids and ammonia kinetics, apparent total-tract nutrient digestibilities and N partitioning, Maillard compounds in feed and feces, plasma AA, and 15N natural enrichment were measured. Data were analyzed using analysis of variance according to the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Extrusion without additive during pretreatment led to higher contents of Maillard compounds in the blend, a lower enzymatic CP degradability, a numerically lower ammonia content in ruminal fluid, and a trend of higher plasma EAA concentration, all suggesting a decrease in degradability of proteins in the rumen, and a subsequent increase in metabolizable protein supply. Compared with pretreatment without additive, adding reducing sugars or an enzymatic cocktail during pretreatment led to an increase in Maillard compound contents in the extruded blends, and to an increase (+50 mg/L) in rumen ammonia content. With reducing sugars, digestibility of Nɛ-carboxymethyl-lysine was numerically lower, and plasma EAA concentration tended to decrease, suggesting an overprotection of proteins in the intestine. With the enzymatic cocktail, plasma EAA concentration was similar than without additive during pretreatment, suggesting a similar metabolizable protein supply with both treatments. Finally, no change in N partitioning between milk, urine, and feces was observed whatever the diet.


Assuntos
Ração Animal/análise , Bovinos/fisiologia , Dieta/veterinária , Manipulação de Alimentos/métodos , Nitrogênio/metabolismo , Vicia faba , Amônia/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Enzimas , Ácidos Graxos Voláteis/análise , Fezes/química , Feminino , Lactação/efeitos dos fármacos , Leite/química , Rúmen/metabolismo , Açúcares
7.
Chemosphere ; 241: 125098, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31877618

RESUMO

Complete-nitrifying bacteria (comammox) play important roles in nitrogen-overloading aquatic systems. However, the understanding of the environmental relevance is still limited. Here, we studied the responses of comammox bacteria (Nitrospira inopinata) in a tributary of the Yellow River, with the water and sediment, microbial, seasonal, and chemical variations considered. Illumina sequencing indicated that the predominant phyla in the river sediment were Proterobacteria, Bacteroidetes, Actinobacteria, and Chloroflex. Quantitative PCR revealed that N. inopinata-like comammox were approximately twice as abundant in the water during the wet season and in the sediment during the dry season than that of other conditions. Significant correlations were found between the abundance of N. inopinata-like comammox and pH (r = 0.58), temperature (r = 0.63), and dissolved oxygen (r = - 0.77). The abundance of N. inopinata-like comammox was higher than that of ammonia oxidizing archaea (AOA), and lower than that of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Furthermore, a significant correlation was discovered between N. inopinata-like comammox and NOB (r = 0.60), and so was anammox bacteria (r = 0.358). Interestingly, N. inopinata-like comammox also showed positive relationships with denitrifying microbes (r = 0.559).


Assuntos
Bactérias/metabolismo , Nitrificação , Ciclo do Nitrogênio , Estações do Ano , Amônia/metabolismo , Bactérias/citologia , Betaproteobacteria , Sedimentos Geológicos/microbiologia , Nitrogênio/metabolismo , Oxirredução , Filogenia , Rios/microbiologia
8.
ISME J ; 14(1): 12-25, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31481743

RESUMO

We tested the ecosystem functions of microbial diversity with a focus on ammonification (involving diverse microbial taxa) and nitrification (involving only specialized microbial taxa) in forest nitrogen cycling. This study was conducted on a forest slope, in which the soil environment and plant growth gradually changed. We measured the gross and net rates of ammonification and nitrification, the abundance of predicted ammonifiers and nitrifiers, and their community compositions in the soils. The abundance of predicted ammonifiers did not change along the soil environmental gradient, leading to no significant change in the gross ammonification rate. On the other hand,  the abundance of nitrifiers and the gross nitrification rate gradually changed. These accordingly determined the spatial distribution of net accumulation of ammonium and nitrate available to plants. The community composition of predicted ammonifiers gradually changed along the slope, implying that diverse ammonifiers were more likely to include taxa that were acclimated to the soil environment and performed ammonification at different slope locations than specialized nitrifiers. Our findings suggest that the abundance of ammonifiers and nitrifiers directly affects the corresponding nitrogen transformation rates, and that their diversity affects the stability of the rates against environmental changes. This study highlights the role of microbial diversity in biogeochemical processes under changing environments and plant growth.


Assuntos
Amônia/metabolismo , Florestas , Nitrificação , Ciclo do Nitrogênio , Microbiologia do Solo , Compostos de Amônio/metabolismo , Biodiversidade , Ecossistema , Nitratos/metabolismo , Nitrogênio/metabolismo , Oxirredução , Plantas/metabolismo , Solo/química
9.
Chemosphere ; 238: 124526, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31466002

RESUMO

In this paper, for the first time, we show in chloraminated systems, the chloramine decaying proteins (CDP) play an important role in bulk water and biomass (biofilm) in resisting disinfectant. Extracellular polymeric substances in biofilm/biomass are known to protect microbes from disinfectants and toxic materials, but the exact mechanism(s) is/are not known. Starting with the seed from a nitrifying chloraminated reactor, two 5 L reactors were fed intermittently with either chloramine or ammonia containing nutrient solution. The degree of nitrification increased with time in both reactors despite an increase in soluble CDP in the chloraminated reactor, while soluble CDP decreased in the ammoniated one. The suspended biomass collected after eight months of operation from chloraminated reactor contained CDP and responded to short-term chloramine stress (1.5 h with initial 1.5 mg-Cl2·L-1) by the additional production of soluble CDP. The suspended biomass from ammoniated reactor neither contained CDP nor produced soluble CDP as a stress response. The production, release and accumulation of CDP in biomass (biofilm) could be one of several mechanisms microbes use to defend against disinfectants (stress). The new understanding will pave the way for better disinfection management and better design of experiments.


Assuntos
Biofilmes , Biomassa , Reatores Biológicos/microbiologia , Cloraminas/metabolismo , Cloraminas/farmacologia , Proteínas/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Amônia/metabolismo , Biofilmes/efeitos dos fármacos , Desinfetantes/farmacologia , Nitrificação
10.
Chemosphere ; 239: 124742, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31514005

RESUMO

Anaerobic ammonium oxidation coupled to Fe(III) reduction, termed Feammox, is a newly identified microbial process that occurs in nitrogen and iron cycles. As the seasonal distribution of Feammox in different ecosystem habitats has not been fully explored, this study investigated the potential Feammox rates and the diversity and abundance of iron reducing bacteria (IRB) in three habitats during two seasons by using isotope tracing technique and molecular analysis, respectively. Results showed that potential Feammox rates vary both seasonally and spatially, having relatively higher rates in summer (0.05-0.19 mg N kg-1 d-1) and lower rates in winter (0.02-0.09 mg N kg-1 d-1). In addition, relatively higher and lower rates were observed in farmland soils (0.09-0.19 mg N kg-1 d-1) and river sediments (0.02-0.05 mg N kg-1 d-1), respectively. The abundance and diversity of IRB were also found to vary both spatially and seasonally. Furthermore, the results show that Feammox may transform nitrogen at a rate of approximately 2.4-22.5 kg N ha-1 yr-1 within the investigated area. It is considered that the soil moisture, the Fe(III) content, and the total organic carbon are important factors controlling Feammox and IRB. Overall, these results extend current scientific knowledge about nitrogen and iron cycles in ecosystem habitats.


Assuntos
Amônia/metabolismo , Bactérias/metabolismo , Ferro/metabolismo , Microbiologia do Solo , Bactérias/genética , Biodiversidade , China , Ecossistema , Fazendas , Nitrogênio/análise , Nitrogênio/metabolismo , Ciclo do Nitrogênio , Oxirredução , RNA Ribossômico 16S , Rios , Estações do Ano , Solo/química , Análise Espaço-Temporal
11.
Chemosphere ; 240: 124974, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726613

RESUMO

In this research, the continuous physiological changes of zebrafish (Danio rerio) in 0.1 µg/L thallium (Tl) in 15 days were investigated. The results showed that Tl(I) stress had a significant positive linear correlation with zebrafish ammonia nitrogen excretion (ANE) (p < 0.001), and the mean value of ANE in Tl(I) treatment (435 ±â€¯227 mg/kg/h) was approximately 2 times higher than in the control group (239 ±â€¯168 mg/kg/h), which suggested that ANE was suitable for Tl(I) stress assessment. A substantial difference based on oxygen consumption rate (OCR) between the control group (587 ±â€¯112 mg/kg/h) and Tl(I) treatment (260 ±â€¯88 mg/kg/h) with a high significance p < 0.001 could be observed, and the results indicated that Tl(I) played a negative role in OCR of zebrafish. The characteristics of both ANE and OCR changes under slight Tl(I) stress could be reflected by the ammonia quotient (AQ). It was noteworthy that AQ increased rapidly in first 6 h from 0.66 to 4.50, which was 3 times higher than 1.2, indicating rapid increase in both anaerobic energy utilization and protein metabolism in 0.1 µg/L Tl(I) exposure. It is concluded that the physiological changes of zebrafish based on metabolism can be regarded as a sensitive biological indicator of Tl(I) pollution, which could work as a substitute of potassium that disrupts the normal biological metabolism in the process of transport.


Assuntos
Tálio/toxicidade , Peixe-Zebra/metabolismo , Amônia/metabolismo , Animais , Cinética , Nitrogênio/metabolismo , Consumo de Oxigênio/fisiologia , Fatores de Tempo , Peixe-Zebra/fisiologia
12.
J Environ Sci (China) ; 86: 120-130, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31787176

RESUMO

The abundance of ammonia-oxidizing bacteria and archaea and their amoA genes from the aerobic activated sludge tanks, recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant (WWTP) was determined. Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles, which showed that each population had a consistent profile although the abundance of individual members varied. In the aerobic tanks, the ammonia-oxidizing bacterial (AOB) population was more than 350 times more abundant than the ammonia-oxidizing archaeal (AOA) population, however in the digesters, the AOA population was more than 10 times more abundant. Measuring the activity of the amoA gene expression of the two populations using RT-PCR also showed that the AOA amoA gene was more active in the digesters than in the activated sludge tanks. Using batch reactors and ddPCR, amoA activity could be measured and it was found that when the AOB amoA activity was inhibited in the anoxic reactors, the expression of the AOA amoA gene increased fourfold. This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.


Assuntos
Amônia/metabolismo , Archaea/genética , Esgotos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/microbiologia , Poluentes Químicos da Água/metabolismo , Bactérias/genética , Eletroforese em Gel de Gradiente Desnaturante
13.
Huan Jing Ke Xue ; 40(6): 2954-2960, 2019 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854691

RESUMO

Dewatered sludge often contains abundant antibiotics, and such contaminants can potentially affect the nitrogen fertilizer value of sludge-derived vermicompost. For this purpose, the aims of this study were to investigate the effects of different tetracycline concentrations in sludge on the nitrification rate and abundance and community characteristics of ammonia oxidizers during vermicomposting. Four sludge treatments with different concentrations of tetracycline (0, 100, 500, and 1000 mg·kg-1) were used, and data were collected to reveal the mechanism regarding the ammonia oxidization of sludge in the vermicomposting system. The results showed that the high concentration of tetracycline (1000 mg·kg-1) significantly inhibited the nitrification rate of vermicomposting (P<0.05), but no significant effect was observed in the low concentration treatments. Compared with ammonia-oxidizing bacteria (AOB), ammonia oxidizing archaea (AOA) were detected as the dominant microorganisms involved in the ammonia oxidation process during vermicomposting. In addition, the abundances of amoA genes were significantly elevated (P<0.05) in the treatments with 100 mg·kg-1 tetracycline, but values significantly decreased with the further increments of tetracycline concentrations (P<0.05). The results obtained from high-throughput sequencing revealed that the community diversity and structure of AOA and AOB were strongly modified by tetracycline concentrations, and a negative correlation relationship was detected between the tetracycline concentrations and the α diversity of AOA.


Assuntos
Amônia/metabolismo , Antibacterianos/análise , Compostagem/métodos , Esgotos/microbiologia , Tetraciclina/análise , Animais , Archaea/classificação , Bactérias/classificação , Nitrificação , Oligoquetos , Oxirredução , Filogenia , Microbiologia do Solo
14.
Environ Pollut ; 255(Pt 2): 113258, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31669955

RESUMO

Ammonia oxidation is the rate-limiting step in nitrification process and dominated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). In the present study, a highly enriched culture of AOA was obtained from urban polluted water in Shahe River, Shenzhen, China. The optimum growth conditions were identified by orthogonal analysis as 37 °C, with pH 7.0 and initial ammonia concentration of 1.0 mM. Under these conditions, the highest abundance of AOA was obtained as 4.6 × 107 copies/ng DNA. Growth of AOA in polluted river water showed significant reduction in ammonia concentration in AOA-enriched cultures without antibiotics after 10 days of incubation, while synchronous increase in nitrate concentration was up to 12.7 mg/L. However, AOA-enriched by antibiotic showed insignificant changes in ammonia or nitrite concentration. This study showed that AOB play an important role in ammonia oxidation of polluted river water, and AOA alone showed insignificant changes in ammonia or nitrite concentrations. Therefore, the ammonia oxidation performance of natural water could not be improved by adding high concentration AOA bacterial liquid.


Assuntos
Amônia/metabolismo , Archaea/metabolismo , Biodegradação Ambiental , Poluentes Químicos da Água/metabolismo , Bactérias/genética , Betaproteobacteria , China , Nitrificação , Oxirredução , Filogenia , Rios/microbiologia , Microbiologia do Solo
15.
Environ Sci Pollut Res Int ; 26(36): 37082-37091, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31745784

RESUMO

Municipal solid waste landfills are not only a crucial source of global greenhouse gas emissions; they also produce large amounts of ammonia (NH3), hydrogen sulfide, and other odorous gases that negatively affect the regional environment. Several types of methane-oxidizing bacteria (MOB) were proved to be effective in mitigating methane emission from landfills. Nevertheless, more MOB species and their technical parameters for best mitigating methane still need to be explored. In landfills, methane is simultaneously generated with ammonia, which may impede the CH4 bio-oxidizing process of MOB. However, very limited studies examined the enhancement of methane reduction by introducing ammonia-oxidizing bacteria (AOB) in landfills. In this study, two enriched MOB cultures were gained from a typical municipal solid waste landfill, and then were cultured with three strains of ammonia-oxidizing bacteria (AOB). The MOB enrichment culture used in this work includes Methylocaldum, Methylocystaceae, and Methyloversatilis, with a methane oxidation capacity of 43.6-65.0%, and the AOB includes Candida ethanolica, Bacillus cereus, and Alcaligenes faecalis. The effects on the emission reduction of both NH3 and CH4 were measured using self-made landfill-simulating equipment, as MOB, AOB, and a MOB-AOB mixture were added to the soil cover of the simulation equipment. The concentrations of CH4 and NH3 in the MOB-AOB mixture group decreased sharply, and the CH4 and NH3 concentration was 76.4% and 83.7% of the control group level. We also found that addition of AOB can help MOB oxidize CH4 and improve the emission reduction effect.


Assuntos
Poluentes Atmosféricos/análise , Amônia/metabolismo , Metano/metabolismo , Eliminação de Resíduos , Instalações de Eliminação de Resíduos , Amônia/análise , Metano/análise , Methylococcaceae , Oxirredução , Solo , Microbiologia do Solo , Resíduos Sólidos
16.
Environ Pollut ; 255(Pt 2): 113321, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31610515

RESUMO

Ionic liquids (ILs) are extensively used in several chemistry fields. And research about the effects of ILs on soil microbes is needed. In this study, brown soil was exposed to 1-butyl-3-methylimidazolium bromide ([C4mim]Br), 1-hexyl-3-methylimidazolium bromide ([C6mim]Br) and 1-decyl-3-methylimidazolium bromide ([C10mim]Br). The toxicities of the three ILs are evaluated by measuring the soil culturable microbial number, enzyme activity, microbial diversity and, abundance of the ammonia monooxygenase (amoA) genes of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Results showed that all tested ILs caused a decrease in culturable microbial abundance. Tested ILs exposure inhibit urease activity and promote acid phosphatase and ß-glucosidase activities. Tested ILs reduced soil microbial diversity and the abundances of AOB-amoA and AOA-amoA genes significantly. After a comparison of the integrated biomarker response (IBR) index, the toxicities of tested ILs to soil microorganisms were as follows: [C10mim]Br > [C6mim]Br > [C4mim]Br. Among all collected biomarkers, the abundance of the AOA-amoA gene was the most sensitive one and was easily affected after ILs exposure.


Assuntos
Archaea/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Boratos/toxicidade , Brometos/toxicidade , Imidazóis/toxicidade , Líquidos Iônicos/toxicidade , Fosfatase Ácida/metabolismo , Amônia/metabolismo , Glucosidases/metabolismo , Oxirredução , Oxirredutases/genética , Filogenia , Solo/química , Microbiologia do Solo , Urease/antagonistas & inibidores
17.
Syst Appl Microbiol ; 42(6): 126021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31623889

RESUMO

During long-term extra-terrestrial missions, food is limited and waste is generated. By recycling valuable nutrients from this waste via regenerative life support systems, food can be produced in space. Astronauts' urine can, for instance, be nitrified by micro-organisms into a liquid nitrate fertilizer for plant growth in space. Due to stringent conditions in space, microbial communities need to be be defined (gnotobiotic); therefore, synthetic rather than mixed microbial communities are preferred. For urine nitrification, synthetic communities face challenges, such as from salinity, ureolysis, and organics. In this study, a synthetic microbial community containing an AOB (Nitrosomonas europaea), NOB (Nitrobacter winogradskyi), and three ureolytic heterotrophs (Pseudomonas fluorescens, Acidovorax delafieldii, and Delftia acidovorans) was compiled and evaluated for these challenges. In reactor 1, salt adaptation of the ammonium-fed AOB and NOB co-culture was possible up to 45mScm-1, which resembled undiluted nitrified urine, while maintaining a 44±10mgNH4+-NL-1d-1 removal rate. In reactor 2, the nitrifiers and ureolytic heterotrophs were fed with urine and achieved a 15±6mg NO3--NL-1d-1 production rate for 1% and 10% synthetic and fresh real urine, respectively. Batch activity tests with this community using fresh real urine even reached 29±3mgNL-1d-1. Organics removal in the reactor (69±15%) should be optimized to generate a nitrate fertilizer for future space applications.


Assuntos
Reatores Biológicos/microbiologia , Microbiota , Nitrificação , Urina/química , Eliminação de Resíduos Líquidos/métodos , Amônia/metabolismo , Comamonadaceae/metabolismo , Delftia acidovorans/metabolismo , Nitritos/metabolismo , Nitrobacter/metabolismo , Nitrosomonas europaea/metabolismo , Pseudomonas fluorescens/metabolismo , Ureia/metabolismo
18.
Aquat Toxicol ; 216: 105294, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31585273

RESUMO

Many ecologically important fishes, including mahi-mahi (Coryphaena hippurus), and their offspring were directly exposed to crude oil following the Deepwater Horizon (DWH) oil spill. Early life stage fish are especially vulnerable to the toxicity of crude oil-derived polycyclic aromatic hydrocarbons (PAHs). In teleosts, yolk sac proteins are the main energy source during development and are usually catabolized into ammonia or urea among other byproducts. Although excretion of these waste products is sensitive to oil exposure, we know little about the underlying mechanisms of this process. In this study, we examined the effects of crude oil on ammonia and urea handling in the early life stages of mahi. Mahi embryos exposed to 30-32 µg L-1 ∑PAH exhibited increased urea excretion rates and greater accumulation of urea in the tissues before hatch suggesting that ammonia, which is highly toxic, was converted into less-toxic urea. Oil-exposed embryos (6.3-32 µg L-1 ∑PAH) displayed significantly increased tissue ammonia levels at 42 hpf and upregulated mRNA levels of ammonia transporters (Rhag, Rhbg and Rhcg1) from 30 to 54 hpf. However, despite increased accumulation and higher expression of ammonia transporters, the larvae exposed to higher ∑PAH (30 µg L-1 ∑PAH) showed reduced ammonia excretion rates after hatch. Together, the increased production of nitrogenous waste reinforces previous work that increased energy demand in oil-exposed embryos is fueled, at least in part, by protein metabolism and that urea synthesis plays a role in ammonia detoxification in oil-exposed mahi embryos. To our knowledge, this study is the first to combine physiological and molecular approaches to assess the impact of crude-oil on both nitrogenous waste excretion and accumulation in the early life stages of any teleosts.


Assuntos
Amônia/metabolismo , Estágios do Ciclo de Vida/efeitos dos fármacos , Perciformes/crescimento & desenvolvimento , Perciformes/metabolismo , Poluição por Petróleo/análise , Petróleo/toxicidade , Ureia/metabolismo , Animais , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Larva/efeitos dos fármacos , Perciformes/genética , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Poluentes Químicos da Água/toxicidade
19.
Appl Microbiol Biotechnol ; 103(21-22): 9131-9141, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31515598

RESUMO

The biological treatment of oil refinery effluents in wastewater treatment plants (WWTPs) relies on specialized bacteria contributing to remove organic load, nitrogen, sulfur, and phosphorus compounds. Knowledge about bacterial dynamics in WWTPs and how they affect the performance of the wastewater treatment is limited, particularly in tropical countries. The bacterial communities from three compartments of an oil refinery WWTP in Uran, India, were assessed using 16S-metabarcoding, in winter and monsoon seasons, upstream (from the surge pond) and downstream the biotower (clarifier and guard pond), to understand the effects of seasonal variations in WWTP's efficiency. The organic load and ammonia levels of the treated wastewater increased by 3- and 9-fold in the monsoon time-point. A decreased abundance and diversity of 47 genera (325 OTUs) comprising ammonia and nitrite oxidizing bacteria (AOB, NOB, denitrifiers) was observed in the monsoon season downstream the biotower, whereas 23 OTUs of Sulfurospirillum, Desulfovibrio, and Bacillus, putatively performing dissimilatory nitrate reduction to ammonia (DNRA), were 3-fold more abundant in the same compartments (DNRA/denitrifiers winter ratio < 0.5 vs. monsoon ratio around 3). The total abundance of reported sulfate- and sulfite-reducing bacteria also increased 250- and 500-fold downstream the biotower, in the monsoon time-point. Bacteria performing DNRA may thus outcompete denitrification in this WWTP, limiting the biodegradation process. The alterations detected in bacterial populations involved in the removal of nitrogen and sulfur species evidenced a reduced quality of the released wastewater and may be good candidates for the following monitoring strategies and optimization of the wastewater treatment.


Assuntos
Bactérias/isolamento & purificação , Microbiota , Águas Residuárias/microbiologia , Amônia/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Desnitrificação , Índia , Nitratos/metabolismo , Nitritos/metabolismo , Petróleo/metabolismo , Filogenia , Estações do Ano
20.
Ecotoxicol Environ Saf ; 185: 109689, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31550566

RESUMO

Nitrification inhibition as an alleviation tool to decrease nitrogen (N) losses and increase N use efficiency (NUE) as well as reducing NO3- accumulation in plants is a promising technology. No study thus far has directly or indirectly to use the secondary metabolites extracted from Moringa (Moringa oleifera Lam) seeds as nitrification inhibitors. Moringa seed extract (MSE) was studied based on its content of phenolic compounds (PC) and for its antioxidant characteristic. A 2-year field experiment and 30-day incubation experiment were conducted with three treatments of control (CK), N fertilizer (300 kg N ha-1 and 200 mg N kg-1 soil for the field and incubation experiment, respectively), and N fertilizer with MSE (500 ppm as a TPC) to investigate the responses of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to MSE and the consequences for NUE and NO3- accumulation in potato tubers. Total phenolics amount was 144 mg gallic acid equivalent g-1 MSE, while flavonoid contents were 76.6 quercetin equivalent g-1 MSE. MSE showed antioxidant activity that was comparable to the standard antioxidants TBHQ and gallic acid. MSE application with N fertilizer retarded the nitrification process, as indicated by a higher NH4+-N and lower NO3--N content, compared with N fertilizer application alone. NH4+-N content reduced to initial CK level on Day 20 under N fertilizer application alone. However, NH4+-N content decreased to initial control level on Day 30 when MSE was applied. The mechanisms resulted from curbing AOB growth by phenolic compounds (TPC, TF, TAC), leading to a delay in nitrification process. AOB increased significantly when N fertilizer was applied alone; on the contrary, AOA was not sensitive to N fertilizer (with and without MSE). Increase in NUE from 37.5% to 66.3% in potato plants under MSE application with N fertilizer was also observed compared with N fertilizer application alone. The highest NO3- accumulation (569 mg NO3- kg-1) in tubers was recorded under N fertilizer application without MSE. MSE application significantly decreased NO3- accumulation (92 mg NO3- kg-1) in tubers which is lower than the maximum value of accepting tubers (200 mg NO3- kg-1). The highest average of N uptake, fresh and dry weight, carotenoids, chlorophyll a, chlorophyll b and nitrate reductase activity was recorded when MSE was applied with N fertilizer. Accordingly, using of Moringa extracted secondary metabolites to suppress AOB growth in the soil is a significant strategy to reduce nitrification rate and N loss from soils, and therefore increase NUE as well as reducing NO3- accumulation in potato tubers.


Assuntos
Amônia/metabolismo , Antioxidantes/farmacologia , Moringa/química , Nitratos/metabolismo , Nitrogênio/metabolismo , Sementes/química , Solanum tuberosum/efeitos dos fármacos , Antioxidantes/isolamento & purificação , Clorofila A/metabolismo , Fertilizantes/análise , Moringa/metabolismo , Nitrificação , Oxirredução , Sementes/metabolismo , Solo/química , Microbiologia do Solo , Solanum tuberosum/metabolismo
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