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1.
Enhancing mainstream nitrogen removal by employing nitrate/nitrite-dependent anaerobic methane oxidation processes.
Liu, T, Hu, S, Guo, J
Critical reviews in biotechnology. 2019;(5):732-745
Abstract
Due to serious eutrophication in water bodies, nitrogen removal has become a critical stage for wastewater treatment plants (WWTPs) over past decades. Conventional biological nitrogen removal processes are based on nitrification and denitrification (N/DN), and are suffering from several major drawbacks, including substantial aeration consumption, high fugitive greenhouse gas emissions, a requirement for external carbon sources, excessive sludge production and low energy recovery efficiency, and thus unable to satisfy the escalating public needs. Recently, the discovery of anaerobic ammonium oxidation (anammox) bacteria has promoted an update of conventional N/DN-based processes to autotrophic nitrogen removal. However, the application of anammox to treat domestic wastewater has been hindered mainly by unsatisfactory effluent quality with nitrogen removal efficiency below 80%. The discovery of nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) during the last decade has provided new opportunities to remove this barrier and to achieve a robust system with high-level nitrogen removal from municipal wastewater, by utilizing methane as an alternative carbon source. In the present review, opportunities and challenges for nitrate/nitrite-dependent anaerobic methane oxidation are discussed. Particularly, the prospective technologies driven by the cooperation of anammox and n-DAMO microorganisms are put forward based on previous experimental and modeling studies. Finally, a novel WWTP system acting as an energy exporter is delineated.
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2.
A generic individual-based model can predict yield, nitrogen content, and species abundance in experimental grassland communities.
Faverjon, L, Escobar-Gutiérrez, A, Litrico, I, Julier, B, Louarn, G
Journal of experimental botany. 2019;(9):2491-2504
Abstract
Functional-structural plant models are increasingly being used to analyse relationships between plant functioning and the topological and spatial organisation of their modular structure. In this study, the performance of an individual-based model accounting for the the architecture and population dynamics of forage legumes in multi-species grasslands was assessed. Morphogenetic shoot and root parameters were calibrated for seven widely used species. Other model parameters concerning C and N metabolism were obtained from the literature. The model was evaluated using a series of independent experiments combining the seven species in binary mixtures that were subject to regular defoliation. For all the species, the model could accurately simulate phytomer demography, leaf area dynamics, and root growth under conditions of weak competition. In addition, the plastic changes induced by competition for light and N in terms of plant development, leaf area, N uptake, and total plant biomass were correctly predicted. The different species displayed contrasting sensitivities to defoliation, and the model was able to predict the superior ability of creeping species to sustain regular defoliation. As a result of competition and management, the balance between species changed over time and was strongly dependent on the pair of species used. The model proved able to capture these differences in community dynamics. Overall, the results demonstrate that integrating the individual components of population dynamics in a process-based model can provide good predictive capacity regarding mixtures of cultivated species.
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3.
Influence of nitrogen status in wine alcoholic fermentation.
Gobert, A, Tourdot-Maréchal, R, Sparrow, C, Morge, C, Alexandre, H
Food microbiology. 2019;:71-85
Abstract
Nitrogen is an essential nutrient for yeast during alcoholic fermentation. Nitrogen is involved in the biosynthesis of protein, amino acids, nucleotides, and other metabolites, including volatile compounds. However, recent studies have called several mechanisms that regulate its role in biosynthesis into question. An initial focus on S. cerevisiae has highlighted that the concept of "preferred" versus "non-preferred" nitrogen sources is extremely variable and strain-dependent. Then, the direct involvement of amino acids consumed in the formation of proteins and volatile compounds has recently been reevaluated. Indeed, studies have highlighted the key role of lipids in nitrogen regulation in S. cerevisiae and their involvement in the mechanism of cell death. New winemaking strategies using non-Saccharomyces yeast strains in co- or sequential fermentation improve nitrogen management. Indeed, recent studies show that non-Saccharomyces yeasts have significant and specific needs for nitrogen. Moreover, sluggish fermentation can occur when they are associated with S. cerevisiae, necessitating nitrogen addition. In this context, we will present the consequences of nitrogen addition, discussing the sources, time of addition, transcriptome changes, and effect on volatile compound composition.
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4.
New discoveries in bacterial N-glycosylation to expand the synthetic biology toolbox.
Nothaft, H, Szymanski, CM
Current opinion in chemical biology. 2019;:16-24
Abstract
Historically, protein glycosylation was believed to be restricted to eukaryotes, but now is abundantly represented in all three domains of life. The first bacterial N-linked glycosylation system was discovered in the Gram-negative pathogen, Campylobacter jejuni, and subsequently transferred into the heterologous Escherichia coli host beginning a new era of synthetic bacterial glycoengineering. Since then, additional N-glycosylation pathways have been characterized resembling the classical C. jejuni system and unconventional new approaches for N-glycosylation have been uncovered. These include cytoplasmic protein modification, direct glycan transfer to proteins, and use of alternate amino acid acceptors, deepening our understanding of the vast mechanisms bacteria possess for protein modification and providing opportunities to expand the glycoengineering toolbox for designing novel vaccine formulations and protein therapeutics.
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5.
Integration of sulfate assimilation with carbon and nitrogen metabolism in transition from C3 to C4 photosynthesis.
Jobe, TO, Zenzen, I, Rahimzadeh Karvansara, P, Kopriva, S
Journal of experimental botany. 2019;(16):4211-4221
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Abstract
The first product of sulfate assimilation in plants, cysteine, is a proteinogenic amino acid and a source of reduced sulfur for plant metabolism. Cysteine synthesis is the convergence point of the three major pathways of primary metabolism: carbon, nitrate, and sulfate assimilation. Despite the importance of metabolic and genetic coordination of these three pathways for nutrient balance in plants, the molecular mechanisms underlying this coordination, and the sensors and signals, are far from being understood. This is even more apparent in C4 plants, where coordination of these pathways for cysteine synthesis includes the additional challenge of differential spatial localization. Here we review the coordination of sulfate, nitrate, and carbon assimilation, and show how they are altered in C4 plants. We then summarize current knowledge of the mechanisms of coordination of these pathways. Finally, we identify urgent questions to be addressed in order to understand the integration of sulfate assimilation with carbon and nitrogen metabolism particularly in C4 plants. We consider answering these questions to be a prerequisite for successful engineering of C4 photosynthesis into C3 crops to increase their efficiency.
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6.
Elucidating the mechanism of the structure-dependent enzymatic activity of Fe-N/C oxidase mimics.
Wang, Y, Zhang, Z, Jia, G, Zheng, L, Zhao, J, Cui, X
Chemical communications (Cambridge, England). 2019;(36):5271-5274
Abstract
Herein, we develop an Fe-N/C-CNT nanomaterial with Fe-N3 units as a paradigm for excellent oxidase mimics by theoretical prediction and experimental implementation. The mechanism of the structure-dependent enzymatic activity is systematically investigated and elucidated from the perspective of the different configurations of M-Nx models (x = 0, 3, 4, and 5; M = Fe, Co, and Ni).
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7.
Do invasive alien plants differ from non-invasives in dominance and nitrogen uptake in response to variation of abiotic and biotic environments under global anthropogenic change?
Liu, YY, Sun, Y, Müller-Schärer, H, Yan, R, Zhou, ZX, Wang, YJ, Yu, FH
The Science of the total environment. 2019;:634-642
Abstract
Plant invasion is the outcome of complicated interactions of both biotic and abiotic environments (i.e. eutrophication and human-induced propagules) under global anthropogenic change. Here, we want to know why some alien clonal plant species become invasive and others do not in the introduced range with variations of both abiotic and biotic environments under global anthropogenic change. We selected three invasive alien and three co-occurring, non-invasive alien clonal plant species in China, and grew them under the constant or variable soil nutrient environments in a native community with low or high vegetative propagule pressure (i.e. simulating pressure of anthropogenic alien propagules). Invasive alien species produced more biomass than non-invasives. Interestingly, invasive species benefited significantly greater from high propagule pressure than non-invasives. Biomass and evenness of native communities were greater with non-invasive than with invasive target species. Invasive plants showed a greater increase of leaf N and decrease of leaf C: N ratio when subject to variable nutrients in comparison to constant nutrients than non-invasives. The negative effects of variable nutrients on evenness of native communities were significantly greater under invasive than non-invasive target species. Moreover, biomass of native communities was significantly negatively related to biomass of invasive species. Variable nutrients significantly promoted the negative biomass relationship between non-invasive species and native communities under high propagule pressure and the negative biomass-evenness relationship between invasive species and native communities. Our study suggests that soil nutrient variability and vegetative propagule pressure influence the growth and leaf C and N uptake of alien clonal plant species in native experimental communities, especially under the high propagule pressure and nutrient variability. Invasive alien clonal species have higher performance and advantages over non-invasives. Future studies should also test the mechanisms that invasive and non-invasive or native plants differ in native communities of native or introduced ranges in the field.
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8.
How Does Evolution in Phosphorus-Impoverished Landscapes Impact Plant Nitrogen and Sulfur Assimilation?
Prodhan, MA, Finnegan, PM, Lambers, H
Trends in plant science. 2019;(1):69-82
Abstract
Phosphorus (P) fertilisers, made from rock phosphate, are used to attain high crop yields. However, rock phosphate is a finite resource and excessive P fertilisers pollute our environment, stressing the need for more P-efficient crops. Some Proteaceae have evolved in extremely P-impoverished environments. One of their adaptations is to curtail the abundance of ribosomal RNA, and thus protein, and tightly control the acquisition and assimilation of nitrogen (N) and sulfur. This differs fundamentally from plants that evolved in environments where N limits plant productivity, but is likely common in many species that evolved in P-impoverished landscapes. Here, we scrutinise the relevance of these responses towards developing P-efficient crops, focusing on plant species where 'P is in the driver's seat'.
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9.
Effect of Protein-Fortified Diet on Nitrogen Balance in Critically Ill Patients: Results from the OPINiB Trial.
Danielis, M, Lorenzoni, G, Azzolina, D, Iacobucci, A, Trombini, O, De Monte, A, Gregori, D, Beltrame, F
Nutrients. 2019;(5)
Abstract
Nitrogen balance (NB) is considered a good marker of adequate protein intake and it has been suggested to be a good predictor of patients' health outcomes. However, in literature, there is a lack of large randomized trials examining NB-guided protein intake in patients in intensive care units (ICUs). A randomized controlled trial enrolling patients admitted to ICU was done to compare changes in NB. Participants were randomized to a standard or protein-fortified diet (protein intake of 1.8 g/kg/day according to the guidelines of the Society of Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition). The primary endpoint was represented by the NB on Day 1, 3, and study exit. Forty patients were enrolled in the study (19 in the protein-fortified group). The longitudinal analysis showed that, on Day 3, patients randomized to the protein-fortified diet were more likely (p < 0.001) to present better NB (at 3 days, patients in the protein-fortified diet were estimated to have a nitrate value of 5.22 g more than patients in the standard diet, 95% CI 3.86-6.58). The protein-fortified diet was found to be significantly and directly associated with changes in NB in critically ill patients admitted to ICU.
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10.
Impact of Nitrogen Nutrition on Cannabis sativa: An Update on the Current Knowledge and Future Prospects.
Landi, S, Berni, R, Capasso, G, Hausman, JF, Guerriero, G, Esposito, S
International journal of molecular sciences. 2019;(22)
Abstract
Nitrogen (N) availability represents one of the most critical factors affecting cultivated crops. N is indeed a crucial macronutrient influencing major aspects, from plant development to productivity and final yield of lignocellulosic biomass, as well as content of bioactive molecules. N metabolism is fundamental as it is at the crossroad between primary and secondary metabolic pathways: Besides affecting the synthesis of fundamental macromolecules, such as nucleic acids and proteins, N is needed for other types of molecules intervening in the response to exogenous stresses, e.g. alkaloids and glucosinolates. By partaking in the synthesis of phenylalanine, N also directly impacts a central plant metabolic 'hub'-the phenylpropanoid pathway-from which important classes of molecules are formed, notably monolignols, flavonoids and other types of polyphenols. In this review, an updated analysis is provided on the impact that N has on the multipurpose crop hemp (Cannabis sativa L.) due to its renewed interest as a multipurpose crop able to satisfy the needs of a bioeconomy. The hemp stalk provides both woody and cellulosic fibers used in construction and for biocomposites; different organs (leaves/flowers/roots) are sources of added-value secondary metabolites, namely cannabinoids, terpenes, flavonoids, and lignanamides. We survey the available literature data on the impact of N in hemp and highlight the importance of studying those genes responding to both N nutrition and abiotic stresses. Available hemp transcriptomic datasets obtained on plants subjected to salt and drought are here analyzed using Gene Ontology (GO) categories related to N metabolism. The ultimate goal is to shed light on interesting candidate genes that can be further studied in hemp varieties growing under different N feeding conditions and showing high biomass yield and secondary metabolite production, even under salinity and drought.