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1.
Planta ; 253(3): 73, 2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33615406

RESUMEN

MAIN CONCLUSION: A reprogramming of secondary metabolism to acclimate to nitrogen deficiency was seen in grapevine eliciting an accumulation of strigolactones and jasmonate. This response links with photosynthetic compensation and enhanced ripening. In addition to the metabolism directly related to nitrogen assimilation, long-term nitrogen depletion may affect plant secondary metabolism, in turn affecting grapevine performance. In this work, the effect of nitrogen deficit was investigated in V. vinifera cv. Barbera potted vines following three years of deprivation, using a combination of morpho-physiological assessments and mass spectrometry-based untargeted metabolomics. Plants grown under nitrogen limitation showed reduced growth and even more curtailed yields, lowered SPAD values, and a quite preserved leaf gas exchange, compared to plants grown under non-limiting nitrogen availability. Ripening was decidedly accelerated, and berry composition improved in terms of higher sugar and phenolic contents under nitrogen-limiting conditions. Metabolomics showed the broad involvement of secondary metabolism in acclimation to nitrogen deficiency, including a distinctive modulation of the phytohormone profile. Several nitrogen-containing metabolites were down accumulated under nitrogen-limiting conditions, including alkaloids, glucosinolates, hypoxanthine, and inosine. On the other hand, phenylpropanoids showed an accumulation trend. Concerning the recruitment of hormones, nitrogen deprivation elicited an accumulation of strigolactones and jasmonate. Noteworthy, both strigolactones and jasmonates have been previously related to increased photosynthetic efficiency under abiotic stress. Furthermore, the severe reduction of lateral shoot development we recorded in N-deprived vines is consistent with the accumulation of strigolactones. Overall, our results suggest that nitrogen deprivation induced a rather broad metabolic reprogramming, mainly including secondary metabolism and hormones profile, reflected in the modulation of photosynthetic performance, canopy growth, and possibly fruit quality.


Asunto(s)
Nitrógeno/metabolismo , Metabolismo Secundario , Vitis/metabolismo , Frutas/crecimiento & desarrollo , Fotosíntesis , Reguladores del Crecimiento de las Plantas , Hojas de la Planta/metabolismo
2.
J Anim Sci ; 99(2)2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33564882

RESUMEN

Because of its high content of polyphenolic compounds, the dietary inclusion of grape pomace (GP) in ruminant diets can reduce reactive nitrogen (N) and methane emissions and enhance the shelf life and beneficial fatty acids (FAs) content of meat. However, the dietary inclusion of GP beyond a threshold that is still to be determined for feedlot cattle can also compromise nutrient supply and, thus, growth performance. This study investigated the optimum proportion of GP in finishing cattle diets. Nutrient intake and apparent total tract digestion, ruminal pH and fermentation, estimated microbial protein synthesis, route of N excretion, and blood metabolites were measured. Six ruminally fistulated crossbred beef heifers (mean initial body weight ± SD: 714 ± 50.7 kg) were used in a replicated 3 × 3 Latin square with 21-d periods. Dietary treatments were 0%, 15%, and 30% of dietary dry matter (DM) as GP, with diets containing 84%, 69%, and 54% dry-rolled barley grain, respectively. There was a linear increase (P = 0.07) in DM intake and quadratic change (P ≤ 0.01) in neutral detergent fiber (NDF) intake. There was a quadratic change (P ≤ 0.04) in apparent total tract DM, NDF, and crude protein digestibility as dietary GP content increased. However, there were no treatment effects (P ≥ 0.18) on total ruminal short-chain FA concentration and duration and area pH < 6.2, 5.8, and 5.5. Although N intake did not differ (269, 262, 253 g/d; P = 0.33) across dietary treatments, feeding GP led to a tendency for a quadratic change (P ≤ 0.07) in ruminal ammonia-N and plasma urea-N concentrations. Total N excretion also changed (quadratic, P = 0.03) because of changes (quadratic, P = 0.02) in fecal N excretion as urinary excretion of N and urea-N did not differ (P ≥ 0.15) across treatments. Feeding GP led to quadratic changes (P ≤ 0.01) in fecal excretion of fiber-bound N. Microbial N flow and apparent N retention also changed (quadratic, P ≤ 0.04) as dietary GP proportion increased. In conclusion, responses to dietary GP proportion were mostly quadratic with indications that nutrient supply as reflected by changes in apparent total tract nutrient digestibility, microbial N supply, and apparent N retention could be compromised beyond a 15% dietary inclusion level.


Asunto(s)
Rumen , Vitis , Alimentación Animal/análisis , Animales , Bovinos , Dieta/veterinaria , Digestión , Femenino , Fermentación , Hordeum , Nitrógeno/metabolismo , Nutrientes , Rumen/metabolismo
3.
Nat Commun ; 12(1): 830, 2021 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-33547297

RESUMEN

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.


Asunto(s)
Ciclo del Carbono/fisiología , Carbono/química , Chlorobi/metabolismo , Ciclo del Nitrógeno/fisiología , Nitrógeno/química , Synechococcus/metabolismo , Compuestos de Amonio/química , Compuestos de Amonio/metabolismo , Anaerobiosis/fisiología , Procesos Autotróficos , Carbono/metabolismo , Chlorobi/química , Clorofila/química , Clorofila/metabolismo , República Democrática del Congo , Ecosistema , Marcaje Isotópico , Lagos/química , Lagos/microbiología , Nitrificación/fisiología , Nitrógeno/metabolismo , Oxidación-Reducción , Synechococcus/química , Tanzanía
4.
Ecotoxicol Environ Saf ; 208: 111767, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396085

RESUMEN

Ammonia nitrogen and nitrite are two common forms of environmental toxicants for aquatic organisms including crustaceans. The PI3K-AKT pathway is an important intracellular signaling pathway related to cellular stress response, but involvement of this pathway in the immunotoxicological response of decapod crustaceans to aquatic toxicants such as ammonia nitrogen and nitrite still remains enigmatic. In this study, based on transcriptome mining and molecular cloning techniques, three key genes (named as MrPI3K, MrAKT and MrFoxO) in the PI3K-AKT signaling pathway were identified from the giant river prawn Macrobrachium rosenbergii. Sequence homology and phylogenetic analysis revealed that all the three genes harbored signature sequences of corresponding protein families, and shared high levels of similarities with their respective homologs from other species. MrPI3K, MrAKT and MrFoxO all displayed ubiquitous tissue distribution profiles, but their expression levels varied to a great extend among different tissues and between sexes. Following exposure to nitrite (20 mg/L nitrite-N) or ammonia (25 mg/L total ammonia-N) stresses for 24 h and 48 h, the three genes all responded by altering their expression levels at different time points, but they didn't show uniform expression patterns following these stresses, indicating the diversified roles of these genes in different tissues and the complexity of this signaling pathway. Remarkably, MrPI3K and MrAKT were induced only in the hemocytes and intestine, respectively, indicating their specific roles in these organs. Our study demonstrated the potential utility of these genes as biomarkers of acute ammonia or nitrite toxicity in prawns, and also provided evidence that the PI3K-AKT pathway is involved in the immunotoxicological responses to nitrite and ammonia stress in M. rosenbergii.


Asunto(s)
Amoníaco/toxicidad , Nitritos/toxicidad , Palaemonidae/fisiología , Proteínas Proto-Oncogénicas c-akt/genética , Contaminantes Químicos del Agua/toxicidad , Animales , Decápodos/metabolismo , Hemocitos/metabolismo , Nitrógeno/metabolismo , Palaemonidae/metabolismo , Penaeidae/metabolismo , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/metabolismo , Filogenia , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Transcriptoma
5.
Nat Commun ; 12(1): 676, 2021 01 29.
Artículo en Inglés | MEDLINE | ID: mdl-33514729

RESUMEN

Across the evolutionary history of insects, the shift from nitrogen-rich carnivore/omnivore diets to nitrogen-poor herbivorous diets was made possible through symbiosis with microbes. The herbivorous turtle ants Cephalotes possess a conserved gut microbiome which enriches the nutrient composition by recycling nitrogen-rich metabolic waste to increase the production of amino acids. This enrichment is assumed to benefit the host, but we do not know to what extent. To gain insights into nitrogen assimilation in the ant cuticle we use gut bacterial manipulation, 15N isotopic enrichment, isotope-ratio mass spectrometry, and 15N nuclear magnetic resonance spectroscopy to demonstrate that gut bacteria contribute to the formation of proteins, catecholamine cross-linkers, and chitin in the cuticle. This study identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution, and provides a framework for understanding the nitrogen flow from nutrients through bacteria into the insect cuticle.


Asunto(s)
Exoesqueleto/crecimiento & desarrollo , Hormigas/crecimiento & desarrollo , Microbioma Gastrointestinal/fisiología , Herbivoria/fisiología , Simbiosis/fisiología , Aminoácidos/metabolismo , Animales , Hormigas/metabolismo , Hormigas/microbiología , Quitina/biosíntesis , Proteínas de Insectos/biosíntesis , Nitrógeno/metabolismo
6.
Ecotoxicol Environ Saf ; 211: 111911, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33453638

RESUMEN

Cadmium (Cd) toxicity causes severe perturbations in nitrogen (N) uptake and assimilation, and thereby interrupts normal plant growth. Molybdenum (Mo), a necessary trace element, plays important roles in N metabolism through regulating N assimilatory enzymes activities and expressions in higher plants. Taking this into account, a pot experiment was performed to explore the role of Mo in alleviating Cd-induced inhibitory effects on physio-biochemical processes, N metabolism, yield attributes and grain quality characters of two fragrant rice cultivars; Guixiangzhan and Meixiangzhan-2. Both the fragrant rice cultivars were treated with two levels of each Cd concentrations (0 and 100 mg/kg) and Mo treatments (0 and 0.15 mg/kg). The results revealed that Cd toxicity significantly reduced (p < 0.05) plant dry biomass, gaseous exchange attributes, chlorophyll contents, N utilizing and assimilatory enzymes activities, 2-acetyl-1-pyrroline (2AP) contents and grain yield in both cultivars; however, more severe inhibitions were observed in Meixiangzhan-2 than Guixiangzhan. Nevertheless, Mo application alleviated Cd stress and enhanced 2AP content and grain yield by 75.05% and 67.94% in Guixiangzhan and 87.71% and 83.51% in Meixiangzhan-2, respectively compared with no Mo application. Moreover, Mo application improved photosynthesis, chloroplast configuration, soluble protein and proline contents and also strengthened the N assimilatory pathway through efficient NO3- utilization, higher nitrate reductase, nitrite reductase, glutamine synthetase and glutamate synthase activities and transcript levels under Cd stress. Collectively, our results imply that Mo-induced enhancement in N utilization and assimilation improved yield and grain quality characters of fragrant rice cultivars under Cd stress.


Asunto(s)
Cadmio/toxicidad , Molibdeno/metabolismo , Nitrógeno/metabolismo , Oryza/fisiología , Pirroles/metabolismo , Cadmio/metabolismo , Grano Comestible/química , Molibdeno/análisis , Nitrato-Reductasa/metabolismo , Nitrógeno/análisis , Odorantes , Oryza/metabolismo , Perfumes/análisis , Fotosíntesis , Proteínas de Plantas/metabolismo , Prolina/metabolismo
7.
Ecotoxicol Environ Saf ; 211: 111895, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33476851

RESUMEN

To investigate the defensive strategies of clam Cyclina sinensis in response to environmental ammonia exposure, we investigate the 96 h median lethal concentration (LC50-96 h) and the 96 h safe concentration (SC) of total ammonia nitrogen (TAN) for C. sinensis, and on the basis we examined glutamine synthetase (GS) activity, glutamine content, urea content and the antioxidant enzyme activities of super oxide dismutase (SOD) and catalase (CAT) in 96 h at three different levels of TAN as 0 (control), 73.94 (T1) and 227.04 mg/L (T2). Results showed that LC50-96 h and SC for C. sinensis were 65.79 and 6.58 mg/L, respectively. The LC50-96 h and SC of NH3 were 1.70 and 0.17 mg/L, respectively. Ammonia exposure had significantly effects on SOD and CAT activities in the hepatopancreas tissue. Both the level of SOD activity and CAT activity increased with increasing concentration of TAN. No significant differences between T1 and T2 were found in GS activity from 3 h to 96 h after exposed to ammonia, whereas they were significantly higher than those in the control. Both the level of glutamine content in T1 and T2 increased significantly from 6 h to 24 h after exposed to ammonia and they were significantly higher than those in the control. There were no significantly differences were found in the level of urea concentration between T1 and T2 from 6 h to 96 h, while they were significantly higher those in the control. In conclusion, enhancing hepatopancreas antioxidant responses as well as converting ammonia into glutamine and urea worked in combination to allow C. sinensi to defend against acute ammonia exposure.


Asunto(s)
Amoníaco/toxicidad , Bivalvos/fisiología , Amoníaco/metabolismo , Animales , Antioxidantes , Bivalvos/metabolismo , Catalasa , Exposición a Riesgos Ambientales , Glutamato-Amoníaco Ligasa/metabolismo , Glutamina , Hepatopáncreas/metabolismo , Dosificación Letal Mediana , Nitrógeno/metabolismo , Alimentos Marinos , Superóxido Dismutasa/metabolismo , Urea/metabolismo
8.
Ecotoxicol Environ Saf ; 208: 111713, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396044

RESUMEN

A novel Microcystis bloom caused by Microcystis densa has occurred in a typical subtropical reservoir every spring and summer since 2012, and it has caused several ecological and economic losses. To determine the environmental factors that influence the growth and physiological characteristics of M. densa, we investigated the variations in physicochemical factors and M. densa cell density from 2007 to 2017. The results showed that the urea-N concentration increased significantly (from 0.02 ± 0.00-0.20 ± 0.01 mg N l-1), whereas other factors did not vary significantly. NO3--N and urea-N concentrations were higher than the NH4+-N concentration during the M. densa bloom. The nitrogen composition changed, and urea-N and NO3--N became a major nitrogen sources in the reservoir. Water temperature and increased urea-N concentrations were the primary factors that influenced variations in M. densa cell density (45.5%, p < 0.05). Laboratory experiments demonstrated that M. densa cultured with urea-N exhibited a higher maximum cell density (9.8 ± 0.5 × 108 cells l-1), more cellular pigments for photosynthesis (chlorophyll a and phycocyanin) and photoprotection (carotenoid), and more proteins than those cultured with NH4+-N and NO3--N. These results suggested that M. densa cultured with urea-N exhibited preferable growth and physiological conditions. Moreover, M. densa exhibited an increased maximum specific uptake rate (0.93 pg N cell-1 h-1) and reduced half-saturation constant (0.03 mg N l-1) for urea-N compared with NH4+-N and NO3--N, suggesting that M. densa preferred urea-N as its major nitrogen source. These results collectively indicated that the increasing urea-N concentration was beneficial for the growth and physiological conditions of M. densa. This study provided ten years of field data and detailed physiological information supporting the critical effect of urea-N on the growth of a novel bloom species M. densa. These findings helped to reveal the mechanism of M. densa bloom formation from the perspective of dissolved organic nitrogen.


Asunto(s)
Eutrofización , Microcystis/crecimiento & desarrollo , Nitrógeno/metabolismo , Urea/metabolismo , Proteínas Bacterianas/metabolismo , Microcystis/metabolismo , Nitratos/análisis , Nitratos/metabolismo , Nitrógeno/análisis , Nitrógeno/química , Pigmentos Biológicos/metabolismo , Temperatura , Urea/análisis
9.
Ecotoxicol Environ Saf ; 209: 111839, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33385682

RESUMEN

Potato is considered a nitrogen (N) intensive plant with a low N use efficiency (NUE). The current study introduced an excellent approach by combining dicyandiamide (DCD), moringa seed oil (MSO), or zeolite (ZE), with N fertilizer for maximizing potato tuber yields and NUE as well as minimizing tubers nitrate (NO3-) accumulation. The impact of these materials on soil N availability and gaseous emissions (NH3, and N2O) was investigated under incubation conditions. A 2-year field experiment were carried out with seven treatments [without N (control), N fertilizer (350 kg N-urea ha-1 as a recommended dose; UreaRD), 75% of N recommended dose with DCD (Urea75%RD+DCD), Urea75%RD with 2% MSO (Urea75%RD+MSO2%), Urea75%RD with 4% MSO (Urea75%RD+MSO4%), Urea75%RD with 0.5 Mg ZE ha-1 (Urea75%RD+ZER1), and Urea75%RD with 1.0 Mg ZE ha-1 (Urea 75%RD+ZER2)]. We also conducted a 40-days incubation trial with the same treatments; however, urea was added at the rate of 200 mg N kg-1 soil for all treatments, excluding the control. The addition of DCD, MSO, and ZE with urea under incubation conditions delayed the nitrification process, thereby causing a rise in NH4+-N content and a decrease in NO3--N content. Ammonia-oxidizing bacteria (AOB) was inhibited (p ≤ 0.01) in treatments Urea+DCD, Urea+MSO4%, and Urea+ZER2. The highest NUE indexes were recorded in treatment Urea75%RD+DCD. The highest NO3- accumulation (567 mg NO3- kg-1) in potato tubers was recorded in treatment UreaRD. Whilest, the lowest NO3- content (81 mg NO3- kg-1) was in treatment Urea75%RD+DCD. The lowest cumulative N2O emissions and highest cumulative NH3 volatilization were observed in the treatment Urea+DCD under incubation conditions. Our findings demonstrated that N fertilizer rate could be reduced by 25%, while the tuber yields increased with an acceptable limit of NO3- content, resulting in economical, agronomical, and environmental benefits.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Fertilizantes/análisis , Moringa , Nitratos/metabolismo , Nitrógeno/metabolismo , Zeolitas/química , Agricultura , Amoníaco/análisis , Betaproteobacteria , Guanidinas , Nitrificación , Nitrógeno/análisis , Óxidos de Nitrógeno , Suelo , Microbiología del Suelo , Solanum tuberosum , Urea
10.
Food Chem ; 340: 127937, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-32889215

RESUMEN

The objective of this study was to investigate differentially abundant proteins (DAPs) of wheat seeds produced under two nitrogen levels (0 and 240 kg/ha) before and after germination. We selected samples at 8 and 72 h after imbibition (HAI) to identify DAPs by iTRAQ. The results showed 190 and 124 DAPs at 8 and 72 HAI, respectively. Alpha-gliadin and chlorophyll a-b binding protein showed the biggest difference in abundance before and after germination. In GO enrichment analysis, the most significantly enriched GO term was nutrient reservoir activity at 8 HAI and endopeptidase inhibitor activity at 72 HAI. Moreover, many DAPs involved in mobilization of stored nutrients and photosynthesis were mapped to KEGG pathways. Dough development time, dough stability time and seedling chlorophyll content under N240 were significantly higher than those under N0, which validated the results of proteomic analysis. These results are crucial for food nutrition and food processing.


Asunto(s)
Germinación , Proteínas de Plantas/metabolismo , Semillas/fisiología , Triticum/fisiología , China , Clorofila A/metabolismo , Gliadina/metabolismo , Nitrógeno/metabolismo , Proteínas de Plantas/análisis , Proteómica/métodos , Plantones/metabolismo , Semillas/metabolismo , Triticum/metabolismo
11.
Ecotoxicol Environ Saf ; 207: 111246, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32927157

RESUMEN

Soilless revegetation is a cost-effective and eco-friendly method for the ecological restoration of gold mine tailings. However, due to gold mine tailings are high-salty, alkaline and low-nutrient, little research has been done on soilless revegetation of gold mine tailings. The aim of study was to apply soilless revegetation to gold mine tailings, and investigate the changes of physicochemical properties and microbial communities of tailings after soilless revegetation. Six selected herbaceous plants (Melilotus officinalis, Xanthium sibiricum, Festuca elata, Zoysia japonica, Amaranthus tricolor L., Artemisia desertorum) grew well on the bare tailings, and their heights reached as high as 16.28 cm after 90 days. After soilless revegetation, tailings salinity dramatically dropped from 547.15 to 129.24 µS cm-1, and pH went down from 8.68 to 7.59 at most. The content of available phosphorus (AP), available nitrogen (AN) and organic matter (OM) in tailings gradually improved, especially the content of AP and OM increased 53.36% and 52.58%, respectively. Furthermore, microbial metabolic activity and diversity in tailings obviously increased 70.33-264.70% and 1.64-13.97% respectively. The relative abundance of potential plant growth-promoting bacteria increased 1.40-3.05%, while the relative abundance of opportunistic pathogens and halophilic bacteria decreased 10.58-17.03% and 2.98-6.52% respectively. Such variations of microbial communities were beneficial for tailings restoration. This study provided insight into soilless revegetation and its impact on tailings microorganisms, which could be a new strategy for ecological restoration of gold mine tailings.


Asunto(s)
Biodegradación Ambiental , Microbiota , Microbiología del Suelo , Contaminantes del Suelo/análisis , Archaea/metabolismo , Bacterias/metabolismo , Oro/metabolismo , Nitrógeno/metabolismo , Fósforo/metabolismo , Desarrollo de la Planta , Plantas/metabolismo , Poaceae/metabolismo , Suelo/química
12.
Chemosphere ; 262: 128213, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33182078

RESUMEN

Although phosphine is ubiquitously present in anaerobic environments, little is known regarding the microbial community dynamics and metabolic pathways associated with phosphine formation in an anaerobic digestion system. This study investigated the production of phosphine in anaerobic digestion, with results indicating that phosphine production mainly occurred during logarithmic microbial growth. Dehydrogenase and hydrogen promoted the production of phosphine, with a maximum phosphine concentration of 300 mg/m3. The abundance of Ruminococcaceae and Escherichia was observed to promote phosphine generation. The analysis of metabolic pathways based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) and the MetaCyc pathway database revealed the highest relative abundance of replication and repair in genetic information processing; further, the cofactor, prosthetic group, electron carrier, and vitamin biosynthesis were observed to be closely related to phosphine formation. A phylogenetic tree was reconstructed based on the neighbor-joining method. The results indicated the clear evolutionary position of the isolated Pseudescherichia sp. SFM4 strain, adjacent to Escherichia, with a stable phosphate-reducing ability for a maximum phosphine concentration of 26 mg/m3. The response surface experiment indicated that the initial optimal conditions for phosphine production by SFM4 could be achieved with nitrogen, carbon, and phosphorus loads of 6.17, 300, and 10 mg/L, respectively, at pH 7.47. These results provide comprehensive insights into the dynamic changes in the microbial structure, isolated single bacterial strain, and metabolic pathways associated with phosphine formation. They also provide information on the molecular biology associated with phosphorus recycling.


Asunto(s)
Reactores Biológicos/microbiología , Clostridiales/metabolismo , Escherichia/metabolismo , Redes y Vías Metabólicas , Microbiota , Fosfinas/análisis , Anaerobiosis , Clostridiales/genética , Escherichia/genética , Hidrógeno/metabolismo , Redes y Vías Metabólicas/genética , Nitrógeno/metabolismo , Fosfatos/metabolismo , Fosfinas/metabolismo , Fósforo/metabolismo , Filogenia , Aguas del Alcantarillado/microbiología
13.
Artículo en Inglés | MEDLINE | ID: mdl-33327596

RESUMEN

The biological denitrification process is extensively discussed in scientific literature. The process requires anoxic conditions, but the influence of residual dissolved oxygen (DO) on the efficiency is not yet adequately documented. The present research aims to fill this gap by highlighting the effects of DO on the specific denitrification rate (SDNR) and consequently on the efficiency of the process. SDNR at a temperature of 20 °C (SDNR20°C) is the parameter normally used for the sizing of the denitrification reactor in biological-activated sludge processes. A sensitivity analysis of SNDR20°C to DO variations is developed. For this purpose, two of the main empirical models illustrated in the scientific literature are taken into consideration, with the addition of a deterministic third model proposed by the authors and validated by recent experimentations on several full-scale plants. In the first two models, SDNR20°C is expressed as a function of the only variable food:microrganism ratio in denitrification (F:MDEN), while in the third one, the dependence on DO is made explicit. The sensitivity analysis highlights all the significant dependence of SDNR20°C on DO characterized by a logarithmic decrease with a very pronounced gradient in correspondence with low DO concentrations. Moreover, the analysis demonstrates the relatively small influence of F:MDEN on the SDNR20°C and on the correlation between SDNR20°C and DO. The results confirm the great importance of minimizing DO and limiting, as much as possible, the transport of oxygen in the denitrification reactor through the incoming flows and mainly the mixed liquor recycle. Solutions to achieve this result in full-scale plants are reported.


Asunto(s)
Desnitrificación , Modelos Químicos , Oxígeno , Reactores Biológicos , Nitrógeno/metabolismo , Reciclaje , Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos
14.
Proc Biol Sci ; 287(1941): 20202393, 2020 12 23.
Artículo en Inglés | MEDLINE | ID: mdl-33323078

RESUMEN

The upside-down jellyfish Cassiopea engages in symbiosis with photosynthetic microalgae that facilitate uptake and recycling of inorganic nutrients. By contrast to most other symbiotic cnidarians, algal endosymbionts in Cassiopea are not restricted to the gastroderm but are found in amoebocyte cells within the mesoglea. While symbiont-bearing amoebocytes are highly abundant, their role in nutrient uptake and cycling in Cassiopea remains unknown. By combining isotopic labelling experiments with correlated scanning electron microscopy, and Nano-scale secondary ion mass spectrometry (NanoSIMS) imaging, we quantified the anabolic assimilation of inorganic carbon and nitrogen at the subcellular level in juvenile Cassiopea medusae bell tissue. Amoebocytes were clustered near the sub-umbrella epidermis and facilitated efficient assimilation of inorganic nutrients. Photosynthetically fixed carbon was efficiently translocated between endosymbionts, amoebocytes and host epidermis at rates similar to or exceeding those observed in corals. The Cassiopea holobionts efficiently assimilated ammonium, while no nitrate assimilation was detected, possibly reflecting adaptation to highly dynamic environmental conditions of their natural habitat. The motile amoebocytes allow Cassiopea medusae to distribute their endosymbiont population to optimize access to light and nutrients, and transport nutrition between tissue areas. Amoebocytes thus play a vital role for the assimilation and translocation of nutrients in Cassiopea, providing an interesting new model for studies of metabolic interactions in photosymbiotic marine organisms.


Asunto(s)
Dinoflagelados/fisiología , Escifozoos/fisiología , Simbiosis/fisiología , Compuestos de Amonio , Animales , Antozoos , Ecosistema , Nitrógeno/metabolismo , Nutrientes , Fotosíntesis
15.
PLoS One ; 15(12): e0243496, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33362217

RESUMEN

Over the past 109 years, a Montana intermountain bunchgrass prairie annually became warmer (0.7°C) and drier (27%). The temperature and precipitation trends continued since 1978, as we studied nitrogen availability, annual aboveground primary production (ANPP), plant phenology and species composition. Given the annual increase in temperature and decrease in precipitation, ANPP might be expected to decline; however, it increased by 110%, as the period of greatest production (late-May-June) became wetter and cooler, counter to the annual pattern, and this was strongest at lower elevations. Grass production increased by 251%, while dicot production declined by 65%, which increased grass relative abundance by 54%. Summer temperatures increased 12.5% which increased plant senescence by 119% and decreased fall plant regrowth by 68%. More intense summer senescence changed plant species composition in favor of more drought tolerant species. The greater ANPP and summer senescence may increase susceptibility for fire, but fire tolerance of the plant species composition did not change. Invasive plant species increased 108% over the study with annual grasses accounting for >50% of this increase, which further increased summer plant senescence. Therefore, seasonal climate changes at a smaller geographical scale (local), rather than average annual climate changes over a larger geographical scale (regional), may better reflect plant community responses, and this makes ecological forecasting of climate change more difficult.


Asunto(s)
Cambio Climático , Poaceae/crecimiento & desarrollo , Biomasa , Pradera , Nitrógeno/metabolismo , Estaciones del Año , Temperatura
16.
Anim Sci J ; 91(1): e13481, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33161615

RESUMEN

This study investigated the effect of adaptation to grazing in early spring on herbage intake, ruminal fermentation parameters, blood metabolite concentrations, and body weight change in dairy cows. The experiment was conducted on eight rumen-cannulated non-lactating cows in the early spring period. Four cows were adapted to grazing by stocking for 4 hr for 1 week (ADP group). The other cows were kept in a barn during the period (CON group). Then, both groups of cows were stocked together throughout a day on a 1 ha pasture for 3 weeks (experimental period). In the first week of the experimental period, compared to the CON group, the ADP group had a higher herbage intake, ruminal NH3 -N and total VFA concentration, and blood urea concentration, but the NEFA concentration was lower in the ADP group (p < .01). During the subsequent weeks, there were little differences in ruminal fermentation parameters and blood metabolites. Cows in the ADP group maintained their body weight, but cows in the CON group lost 60 kg of body weight in the first week of the experimental period.


Asunto(s)
Adaptación Fisiológica/fisiología , Fenómenos Fisiológicos Nutricionales de los Animales/fisiología , Peso Corporal , Bovinos/metabolismo , Bovinos/fisiología , Ingestión de Alimentos/fisiología , Fermentación , Herbivoria/fisiología , Rumen/metabolismo , Estaciones del Año , Amoníaco/metabolismo , Animales , Nitrógeno de la Urea Sanguínea , Femenino , Nitrógeno/metabolismo , Factores de Tiempo
17.
Chemosphere ; 261: 128172, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33113654

RESUMEN

Nitritation is currently known as a bottleneck for mainstream nitrite shunt or partial nitritation/anammox (PN/A). Here we propose a new approach to selectively eliminate nitrite oxidizing bacteria (NOB) for mainstream nitritation by low-dose ultraviolet-A (UVA) irradiation. The results showed that mainstream nitritation was rapidly achieved within 10 days with UVA irradiation at the dose of 0.87 µE L-1 s-1, and nitrite accumulation ratio (NO2--N/(NO2--N + NO3--N) ×100%) stabilized over 80%. Microbial community analysis revealed that two typical NOB populations (Nitrospira and Ca. Nitrotoga) detected in the control reactor were suppressed efficiently in UVA irradiation reactor, whereas the Nitrosomonas genus of ammonium oxidizing bacteria (AOB) remained at similar level. Intracellular reactive oxygen species (ROS) analysis indicated that NOB-dominant sludge tends to generate more intracellular ROS compared with AOB-dominant sludge in the presence of UVA, leading to the inactivation and elimination of NOB. Additionally, amounts of microalgae found in UVA irradiation reactor could help to suppress NOB by generating ROS during photosynthesis. Briefly, the UVA irradiation approach proposed in this study was shown to be promising in NOB suppression for reliable mainstream nitritation.


Asunto(s)
Bacterias/efectos de la radiación , Reactores Biológicos/microbiología , Nitritos/metabolismo , Rayos Ultravioleta , Eliminación de Residuos Líquidos/métodos , Compuestos de Amonio/metabolismo , Microbiota , Nitrógeno/metabolismo , Nitrosomonas/efectos de la radiación , Oxidación-Reducción , Especies Reactivas de Oxígeno/metabolismo , Aguas del Alcantarillado/microbiología , Eliminación de Residuos Líquidos/instrumentación
18.
Chemosphere ; 261: 128199, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33113666

RESUMEN

A microalgal-bacterial membrane photobioreactor (MB-MPBR) was developed for simultaneous COD and nutrients (N and P) removals from synthetic municipal wastewater in a single stage for a long-term operation over 350 days. The effects of hydraulic retention time (HRT) and N/P ratio on the biological performance were systematically evaluated for the first time. The results showed that a lower N/P ratio (3.9:1) and shorter HRT (2 d) promoted more biomass production, as compared to a high HRT (3 d) and a high N/P ratio (9.7:1). The highest biomass concentration (2.55 ± 0.14 g L-1) and productivity (127.5 mg L-1·d-1) were achieved at N/P ratio of 3.9:1 and HRT of 2 d due to the highest nitrogen and phosphorus loadings under such conditions. A COD and ammonia-N removal efficiency of over 96% and 99%, respectively, were achieved regardless of HRTs and N/P ratios. In the absence of nitrogen or phosphorus deficiency, shorter HRT (2 d) yielded a higher nitrogen and phosphorus uptake but lower removal efficiency. In addition, the imbalance N/P ratio (9.7:1) would decrease nitrogen or phosphorus removal. Overall, the results suggested that it was feasible to simultaneously achieve complete or high removal of COD, nitrogen, and phosphorous in MB-MPBR under the appropriate conditions. This study demonstrated for the first time that MB-MPBR is a promising technology that could achieve a high-quality effluent meeting the discharge standards of COD and nutrients in one single step.


Asunto(s)
Nitrógeno/metabolismo , Fósforo/metabolismo , Fotobiorreactores , Eliminación de Residuos Líquidos/instrumentación , Amoníaco/metabolismo , Análisis de la Demanda Biológica de Oxígeno , Biomasa , Chlorella vulgaris/metabolismo , Microalgas/metabolismo , Nitrógeno/análisis , Fotobiorreactores/microbiología , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química
19.
Int J Food Microbiol ; 335: 108903, 2020 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-33065381

RESUMEN

Societal demand for plant-based foods is increasing. In this context, soya products fermented using lactic acid bacteria (LAB) are appealing because of their potential health and nutritional benefits. The thermophilic LAB Streptococcus thermophilus is an essential starter species in the dairy industry. However, while its physiology is well characterized, little is known about its general metabolic activity or its techno-functional properties when it is grown in soya milk. In this study, S. thermophilus LMD-9 growth, sugar production, and lactic acid production in soya milk versus cow's milk were measured. Additionally, the main metabolic pathways used by the bacterium when growing in soya milk were characterized using a proteomic approach. Streptococcus thermophilus LMD-9 growth decreased soya milk pH, from 7.5 to 4.9, in 5 h. During fermentation, acidification thus occurred in tandem with lactate production and increasing population size (final population: 1.0 × 109 CFU/ml). As growth proceeded, sucrose was consumed, and fructose was produced. The proteomic analysis (LC-MS/MS) of the strain's cytosolic and cell envelope-associated proteins revealed that proteins related to amino acid transport and nitrogen metabolism were the most common among the 328 proteins identified (63/328 = 19.2% of total proteins). The cell-wall protease PrtS was present, and an LMD-9 deletion mutant was constructed by interrupting the prtS gene (STER_RS04165 locus). Acidification levels, growth levels, and final population size were lower in the soya milk cultures when the ΔprtS strain versus the wild-type (wt) strain was used. The SDS-PAGE profile of the soluble proteins in the supernatant indicated that soya milk proteins were less hydrolyzed by the ΔprtS strain than by the wt strain. It was discovered that S. thermophilus can grow in soya milk by consuming sucrose, can hydrolyze soya proteins, and can produce acidification levels comparable to those in cow's milk. This study comprehensively examined the proteomics of S. thermophilus grown in soya milk and demonstrated that the cell-wall protease PrtS is involved in the LAB's growth in soya milk and in the proteolysis of soya proteins, which are two novel findings. These results clarify how S. thermophilus adapts to soya milk and can help inform efforts to develop new fermented plant-based foods with better-characterized biochemical and microbiological traits.


Asunto(s)
Proteínas Bacterianas/metabolismo , Serina Endopeptidasas/metabolismo , Leche de Soja/metabolismo , Streptococcus thermophilus/crecimiento & desarrollo , Streptococcus thermophilus/metabolismo , Animales , Fermentación , Ácido Láctico/análisis , Ácido Láctico/metabolismo , Redes y Vías Metabólicas , Leche/química , Leche/metabolismo , Leche/microbiología , Proteínas de la Leche/metabolismo , Nitrógeno/metabolismo , Proteómica , Leche de Soja/química , Proteínas de Soja/metabolismo , Streptococcus thermophilus/enzimología , Sacarosa/metabolismo , Azúcares/análisis , Azúcares/metabolismo
20.
Anim Sci J ; 91(1): e13455, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33025683

RESUMEN

This study aimed to evaluate nutrient intake and digestibility, enteric methane emission and nitrogen utilization efficiency in Nellore cattle ranked by residual feed intake (RFI). Twenty-four Nellore bulls at 466 ± 24 days of age and with 352 ± 14.6 kg of body weight, classified as low and high RFI, were evaluated. Animals were kept in individual pens for three periods of 28 days and variables were measured. Data were analyzed as repeated measures over time, considering as fixed effects RFI class, period and RFI class x period interaction, and linear (co)variate of age. No significant differences in dry matter or nutrient intake were detected between RFI classes, but total digestible nutrients intake tended to be lower in low RFI animals, and apparent nutrient digestibility was higher in high RFI animals. Partial efficiency of growth tended to be lower in high RFI animals. RFI class did not interfere with enteric methane production or microbial protein synthesis, but fecal nitrogen output was higher in low RFI animals. The greater efficiency of low RFI animals is consequence of lower maintenance requirements, since energy from higher nutrients digestibility in high RFI animals was spent on metabolic processes other than body tissue deposition.


Asunto(s)
Fenómenos Fisiológicos Nutricionales de los Animales , Conducta Animal , Bovinos/metabolismo , Bovinos/fisiología , Dieta/veterinaria , Digestión , Ingestión de Alimentos , Conducta Alimentaria , Tracto Gastrointestinal/metabolismo , Gases de Efecto Invernadero/metabolismo , Metano/metabolismo , Nitrógeno/metabolismo , Animales , Masculino
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