Ammonia Nitrite Research Articles

Effects of intercropping with legume forage on the rhizosphere microbial community structure of tea plants

ContextIntercropping in agriculture is crucial for addressing challenges in intensive tea farming. Forage legumes reduce fertilizer dependence and significantly boost productivity. Currently, intercropping with legumes enhances the environmental conditions of tea plantations and improves tea quality.ObjectiveHowever, the comprehension of the rhizosphere’s impact on the associated microbes and the community structure of tea plants is still somewhat constrained.MethodsHence, four distinct planting methodologies were examined: Monoculture cultivation of Tieguanyin tea plants (MT), Laredo forage soybean (Glycine max Linn.) without partitioning in conjunction with tea (IT), intercropping with tea using plastic partitions (PPIT), and intercropping with tea facilitated by net partitions (NPIT). An absolute quantitative analysis of soil phospholipid fatty acids, labeled with the rhizosphere microbial characteristics of tea plants, was conducted through multi-ion reaction monitoring (MRM). The bacterial and fungal communities were anticipated utilizing the FAPROTAX and FUNG databases, respectively. Gas chromatography was employed to ascertain greenhouse gas emissions across diverse root interaction cultivation systems.Results and conclusionThe rhizospheric influence culminated in a 44.6% increase in total phospholipid fatty acids (PLFAs) and a remarkable 100.9% escalation in the ratio of unsaturated to saturated fatty acids. This rhizospheric enhancement has significantly potentiated the ecological functionalities within the bacterial community, including xylanolysis, ureolysis, nitrogen respiration, nitrogen fixation, nitrite respiration, nitrite ammonification, and nitrate reduction. Mycorrhizomonas, encompassing both ectomycorrhizal and arbuscular forms, has notably colonized the rhizosphere. The interspecific mutualistic interactions within the rhizosphere have resulted in a significant enhancement of plant growth-promoting bacteria, including allorhizobium, bradyrhizobium, rhizobium, burkholderia, gluconacetobacter, and gluconobacter, while concurrently reducing the prevalence of pathogenic microorganisms such as xanthomonas, ralstonia, fusarium, and opportunistic fungi responsible for white and soft rot. The intercropping system showed lower total greenhouse gas emissions than monocultured tea plants, particularly reducing soil CO2 emissions due to complex interspecific rhizosphere interactions. This tea/legume intercropping approach promotes a sustainable ecosystem, enhancing microbial biomass and vitality, which helps suppress rhizospheric pathogens.SignificanceThese findings are instrumental in enhancing our comprehension of the pivotal practical implications of rhizosphere intercropping, thereby optimizing the structure of rhizosphere communities and alleviating the impact of greenhouse gases within croplands.

Development of technology for intensification of oil production using emulsion based on natural gasoline and solutions of nitrite compounds

This article focuses on the issue of enhancing oil production by eliminating asphalt, resin, and paraffin deposits (ARPD). These deposits pose significant challenges, including equipment clogging, reduced well productivity, and increased maintenance costs. Moreover, paraffin deposits can damage well equipment, cause accidents, and halt hydrocarbon production. The study involved laboratory and field experiments at the Uzen field to evaluate the efficiency of removing and dissolving paraffin using an emulsion composed of gas gasoline and nitrite compound solutions. Previous studies conducted at NGDU Uzenneft were critically analyzed for comparison. The scientific innovation of this research lies in the development of an emulsion based on gas gasoline and nitrite compound solutions to remove ARPD. The composition was designed to exclude highly aggressive components. It utilized a previously developed emulsion base and incorporated ammonium nitrite, slightly acidified with hydrogen chloride (0.1% by mass), to promote an exothermic reaction.The effectiveness of this technology was measured by changes in daily oil production rates, the duration of the treatment's effect, and changes in the well productivity coefficient before and after treatment.Results indicate that the developed technology successfully removed paraffin from the bottomhole zone of oil wells and increased oil production in 5 out of 6 wells at the Uzen field. The positive effect lasted 17-27 days, with oil inflow increasing by 17-174%. This led to a total additional oil production of 1528 tons from the five wells. Keywords: bottomhole formation zone; asphalt-resin-paraffin deposits; nitrite composition; surfactants; enhanced oil recovery.

Whole Genome Analysis of Streptomyces spp. Strains Isolated from the Rhizosphere of Vitis vinifera L. Reveals Their Role in Nitrogen and Phosphorus Metabolism

The rhizospheric microorganisms of agricultural crops play a crucial role in plant growth and nutrient cycling. In this study, we isolated two Streptomyces strains, Streptomyces sp. LM32 and Streptomyces sp. LM65, from the rhizosphere of Vitis vinifera L. We then conducted genomic analysis by assembling, annotating, and inferring phylogenomic information from the whole genome sequences. Streptomyces sp. strain LM32 had a genome size of 8.1 Mb and a GC content of 72.14%, while Streptomyces sp. strain LM65 had a genome size of 7.3 Mb and a GC content of 71%. Through ANI results, as well as phylogenomic, pan-, and core-genome analysis, we found that strain LM32 was closely related to the species S. coelicoflavus, while strain LM65 was closely related to the species S. achromogenes subsp. achromogenes. We annotated the functional categories of genes encoded in both strains, which revealed genes involved in nitrogen and phosphorus metabolism. This suggests that these strains have the potential to enhance nutrient availability in the soil, promoting agricultural sustainability. Additionally, we identified gene clusters associated with nitrate and nitrite ammonification, nitrosative stress, allantoin utilization, ammonia assimilation, denitrifying reductase gene clusters, high-affinity phosphate transporter and control of PHO regulon, polyphosphate, and phosphate metabolism. These findings highlight the ecological roles of these strains in sustainable agriculture, particularly in grapevine and other agricultural crop systems.

Carbonate microbialites and chemotrophic microbes: Insights from caves from south‐east China

ABSTRACTChemosynthetic microorganisms facilitate microbialite development in many caves throughout the world. In Youqin Cave and Tian'e Cave, located in the Carboniferous–Triassic carbonates on the South China Block, five Quaternary speleothems (stalagmite, stalactite and cave pearl) that are 2.3 to 11.0 cm long were examined for their petrographic, geochemical and microbiological features to reveal how chemotrophs contribute to microbialite growth. In the speleothems, millimetre‐sized stromatolites, thrombolites and calcified microbial mats are characterized by alternating light, calcitic microlaminae and dark, clay and organic‐rich calcite microlaminae. Filamentous (reticulate, smooth, nodular and helical), coccoid and bacilliform microbes, originally carried into the caves from surface soils, are more common in the dark microlaminae/clots than in the light microlaminae. 16S rRNA gene sequencing shows that the biotas in the microbialites are dominated by chemoorganotrophic heterotrophic bacteria, including primarily Sphingomonas, Crossiella and Acinetobacter, and rare Archaea. Diverse metabolic pathways of these prokaryotes, including ureolysis, denitrification and nitrite ammonification, contributed to increases in localized pH and/or dissolved inorganic carbon in these microenvironments, prompting carbonate precipitation. Development of the cave microbialites was probably controlled by the evolution of the cave microbial community as environmental conditions changed. Microbialite growth was probably mediated by the microorganisms that flourished on the speleothem surfaces during periods of low drip water rates and slow calcite precipitation. The change from microstromatolites to microthrombolites was probably linked to a decrease in cell populations in the microbial communities. These cave microbialites provide clear insights regarding the biogenicity and growth mechanisms of chemosynthetic microbialites. Given their association with chemolithotrophic activities that can date back to the Meso‐Archean, cave microbialites provide insights into the biogenicity and growth mechanisms of chemosynthesis‐based microbialites throughout geological history.

Carbon and nitrogen transformation mechanism and functional microorganisms of sheep manure composting on the Qinghai-Tibet Plateau under different moisture content

In this study, metagenomics technology was used to explore the microbial mechanism and functional microorganisms of carbon and nitrogen transformation during sheep manure composting under 45% (S45) and 60% moisture content (S60) on the Qinghai-Tibet Plateau (QTP). Results showed that the organic carbon oxidation was the main step of carbon transformation during composting, and Corynebacterium, Nocardiopsis, Brachybacterium, Brevibacterium, Luteimonas, Pseudoxanthomonas, and Thermobifida were the main participants in this step. The encoding gene abundance of functional enzymes such as cellulase, glucosidase, and chitinase involved in organic carbon oxidation of S45 was higher than that of S60, which resulted in S45 having a higher lignocellulosic degradation rate. In nitrogen transformation, nitrate reduction was the most important nitrogen transformation step in the early stage. As composting proceeded, nitric oxide reduction, nitrite reduction, and nitrite ammonification gradually enhanced. The abundance of functional genes involved in nitrite reduction and nitric oxide reduction in S45 was lower than that in S60, which would result in lower nitrogen loss and higher alkali-hydrolyzed nitrogen content in S45. Nocardiopsis, Corynebacterium, Pseudomonas, Pseudorhizobium, Planifilum, Sphingobacterium, and Luteimonas were the main participants in denitrification. Cellulomonas, Nocardiopsis, Altererythrobacter, Cellulosimicrobium, Devosia, and Streptomyces were the main participants in nitrite ammonification.

Unraveling the genomic diversity and ecological potential of the genus Demequina: insights from comparative analysis of different saline niche strains

During an investigation of the culturable microbial diversity of sediments with salinity from tidal flats and saline lake, seven strains of the genus Demequina were harvested. The genomic analysis and physiological characteristics of strains of this genus have unveiled their significant potential in degrading complex carbon source such as lignin, hemicellulose, chitin, and oligosaccharides. In addition, these strains show potential abilities in nitrite ammonification and sulfide oxidation. These findings not only improved our understanding of their metabolic model, but also provided valuable insights into their ecological roles. Four new species of the genus Demequina are described: Demequina litoralis sp. nov., with SYSU T00192T designated as the type species; Demequina zhanjiangensis sp. nov., with SYSU T00b26T as the type species; Demequina lignilytica sp. nov., with SYSU T00068T as the type species; and Demequina muriae sp. nov., with EGI L300058T as the type species. Additionally, strains SYSU T0a273, SYSU T00039-1, and SYSU T00039 are identified as different strains of Demequina lignilytica. Our study thus sheds light on the diversity, biological significance, and ecological contribution of the Demequina genus in different habitats.

Diversity and Functional Distribution Characteristics of Myxobacterial Communities in the Rhizosphere of Tamarix chinensis Lour in Ebinur Lake Wetland, China.

Soil salinity and desertification are seriously threatening the ecological environment of Ebinur Lake Wetland. Myxobacteria are the main soil microbes in this wetland. However, it is still unclear if the myxobacterial community structure and diversity can improve the ecological environment of Ebinur Lake Wetland by regulating soil nutrient cycling. Therefore, based on high-throughput sequencing of 16SrRNA gene technology, the composition, function, and diversity of the myxobacterial community in the rhizosphere of Tamarix chinensis Lour in Ebinur Lake Wetland were studied. Rhizosphere soil samples were collected from 10 sampling sites (S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10) for three months (April, July, and October) to explore the main biotic and abiotic factors affecting the diversity and functions of myxobacterial communities. The results revealed that diversity of myxobacterial communities was mainly influenced by the seasons. The diversity of myxobacterial communities was significantly higher in the month of July, as compared to April and October. FAPROTAX functional prediction revealed that, in addition to predation or parasitic functions, myxobacteria were mainly involved in ecological functions, such as nitrite respiration, nitrite ammonification, and nitrogen respiration. The Spearman correlation analysis of the diversity and function of myxobacteria and bacteria showed that there were significant positive correlations between myxobacteria diversity, function, and bacterial diversity. The co-occurrence analysis of myxobacteria and bacterial networks showed that over time, myxobacteria interacted differently with different bacterial networks and jointly regulated the microbial community in the rhizosphere of Tamarix chinensis Lour through predation or cooperation. The redundancy analysis of soil physicochemical factors as well as the myxobacterial community showed that electrical conductivity, exchangeable calcium, and exchangeable potassium were the most important abiotic factors affecting the diversity, structure, and function of the myxobacterial community. These results reveal that myxobacteria may play important roles in degrading nitrogen compounds and regulating the activity of soil microorganisms. This study provides theoretical support for the ecological restoration of Ebinur Lake Wetland and lays the foundation for the future development and utilization of myxobacteria resources.

Marine Bacterial Communities in the Xisha Islands, South China Sea

Oligotrophic marine environments are ecological funnels in marine ecosystems and are essential for maintaining the health and balance of the entire marine ecosystem. Bacterial communities are one of the most important biological populations, which can survive in low-nutrient environments and perform a variety of important ecological functions, such as decomposing and absorbing organic waste in the ocean and converting nitrogen from the atmosphere into a usable nitrogen source, thus maintaining the health of marine ecosystems. The bacterioplankton community composition and potential function were analyzed using 16S rRNA gene amplicon sequencing in oligotrophic coral reef sea areas. The diversity of the bacterial community exhibited significant differences between the four studied regions. Proteobacteria (38.58–62.79%) were the most abundant in all sampling sites, followed by Cyanobacteria (15.41–37.28%), Bacteroidota (2.39–6.67%), and Actinobacteriota (0.45–1.83%). Although bacterioplankton communities presented no difference between surface and bottom water regarding community richness and α-diversity, the bacterial community composition presented significant differences between surface and bottom water regarding β-diversity. Alteromonadales, Rhodospirllales, and Chloroplast were identified as the significantly different communities between the surface and bottom (Q value < 0.01). Bacterial community distribution in different regions was mainly affected by pH, dissolved oxygen, and nutrients. Nitrite ammonification, chitinolysis, predatory or exoparasitic, chloroplasts, chemoheterotrophy, aerobic chemoheterotrophy, phototrophic, compound degradation (mostly nutrients and pollutants), nitrogen cycle, fermentation, and intracellular parasitism were the dominant functions in the four regions.

Effects of fungal agents and biochar on odor emissions and microbial community dynamics during in-situ treatment of food waste

The effects of the co-addition of fungal agents and biochar on physicochemical properties, odor emissions, microbial community structure, and metabolic functions were investigated during the in-situ treatment of food waste. The combined addition of fungal agents and biochar decreased cumulative NH3, H2S, and VOCs emissions by 69.37%, 67.50%, and 52.02%, respectively. The predominant phyla throughout the process were Firmicutes, Actinobacteria, Cyanobacteria, and Proteobacteria. Combined treatment significantly impacted the conversion and release of nitrogen from the perspective of the variation of nitrogen content between different forms. FAPROTAX analysis revealed that the combined application of fungal agents and biochar could effectively inhibit nitrite ammonification and reduce the emission of odorous gases. This work aims to clarify the combined effect of fungal agents and biochar on odor emission and provide a theoretical basis for developing an environmentally friendly in-situ efficient biological deodorization (IEBD) technology.

Solid State Kinetics of Nitrosation Using Native Sources of Nitrite

While many reactive species are known to cause N-nitrosation, trace nitrite (NO2−), which may be present in several excipients, is a source of nitrosating agents in pharmaceutical formulations. In this study we have found that the salt form of NO2− can influence the favored nitrosation conditions and final amount of nitrosamine being formed. Using native levels of NO2−, most likely present as ammonium nitrite (NH4NO2), in microcrystalline cellulose, we have determined the kinetics of nitrosamine formation in solid state with dimethylamine substrate present in metformin, used as model compound. It was found that the competing degradation of NH4NO2 into N2 and H2O limited the amount of nitrosamine formation to a great extent. Empirically modelling the kinetic data predicted reaching at maximum 1.6% conversion over a hypothetical 3-year shelf-life. These results also showed that using other sources of NO2− as spiking reagents, such as NaNO2, may lead to unrealistic worst-case situations when the main form of NO2− in the drug product (DP) under evaluation may be NH4NO2. As well, measuring NO2− in freshly manufactured excipients containing NO2− potentially as NH4NO2 may lead to biased high NO2− content, which is not representative of the actual amounts present at the time of DP manufacture.

Fluorescent property of carbon dots extracted from cigarette smoke and the application in bio-imaging.

Cigarette smoke is one of the six major pollution sources in the room air. It contains large number of particles with size less than 10 nm. There exist carbon dots (CDs) in cigarette smoke which have strong fluorescence and with good bio-compatibility and low toxicity. CDs in cigarette smoke can be applied in bio-imaging which has great potential applications in the integration of cancer diagnosis and treatment. In this paper, CDs were extracted from cigarette smoke. Then, sodium borohydride was added to CDs aqueous solution for reduction and the reduced CDs (R-CDs) were used for biological cell imaging. The results indicate that the CDs with the particle size <10 nm in cigarette smoke are self-assembled by the polymerizated polycyclic aromatic hydrocarbons (PAHs) and ammonium nitrite which are disk nano-structure composed of sp2/sp3 carbon and oxygen/nitrogen groups or polymers. Sodium borohydride can reduce the carbonyl group on the surface of CDs to hydroxyl group and increase the ratio of the Na 1s ratio of the CDs from 1.86 to 7.42. The CDs can emit blue fluorescence under ultraviolet irradiation. After reduction, the R-CDS have the intensity of fluorescence 7.2 times than before and the fluorescence quantum yield increase from 6.13% to 8.86%. The photoluminescence (PL) wavelength of R-CDS have red-shift of 7 nm which was due to the increasing of Na element ratio. The onion epidermal cells labeled with R-CDs show that the CDs could pass through the cell wall into the cell and reach the nucleus. The cell wall and the nucleus could be clearly visualized. CDs also shows low toxicity to human bronchial epithelial cells (BEAS-2B) with good biological activity. The obtained results indicate that the CDs and R-CDs have good fluorescent property which could be used as bio-imaging agent.

Characterization and Testing of Unstable Oxidizers: Ammonium Chlorate and Nitrite

AbstractAmong oxidizers those containing the ammonium cation have the potential of self‐oxidization, making them of special hazard. Herein we examine ammonium nitrite and ammonium chlorate, two ionic compounds with well‐known hazard potential, and compare their explosive performance with related materials. A novel protocol for assessment of explosivity on the gram scale is employed.

Homology modeling and virtual characterization of cytochrome c nitrite reductase (NrfA) in three model bacteria responsible for short-circuit pathway, DNRA in the terrestrial nitrogen cycle.

NrfA is the molecular marker for dissimilatory nitrate reduction to ammonium (DNRA) activity, catalysing cytochrome c nitrite reductase enzyme. However, the limited study has been made so far to understand the structural homology modeling of NrfA protein in DNRA bacteria. Therefore, three model DNRA bacteria (Escherechia coli, Wolinella succinogenes and Shewanella oneidensis) were chosen in this study for in-silico protein modeling of NrfA which roughly consists of similar length of amino acids and molecular weight and they belong to two contrasting taxonomicfamilies (γ-proteobacteria with nrfABCDEFG and ε-proteobacteria with nrfHAIJoperon). Multiple bioinformatic tools were used to examine the primary, secondary, and tertiary structure of NrfA protein using three distinct homology modeling pipelines viz., Phyre2, Swiss model and Modeller. The results indicated that NrfA protein in E. coli, W. succinogenes and S. oneidensis was mostly periplasmic and hydrophilic. Four conserved Cys-X1-X2-Cys-His motifs, one Cys-X1-X2-Cys-Lys haem-binding motif and Ca ligand were also identified in NrfA protein irrespective of three model bacteria. Moreover, 11 identical conserved amino acids sequence was observed for the first time between serine and proline in NrfA protein. Secondary structure of NrfA revealed that α-helices were observed in 77.9%, 73.4%, and 77.4% in E. coli, W. succinogenes and S. oneidensis, respectively. Ramachandran plot showed that number of residue in favored region in E. coli, W. succinogenes and S. oneidensis was 97.03%, 97.01% and 97.25%, respectively. Our findings also revealed that among three pipelines, Modeller was considered the best in-silico tool for prediction of NrfA protein. Overall, significant findings of this study may aid in the identification of future unexplored DNRA bacteria containing cytochrome c nitrite reductase. The NrfA system, which is linked to respiratory nitrite ammonification, provides an analogous target for monitoring less studied N-retention processes, particularly in agricultural ecosystems. Furthermore, one of the challenging research tasks for the future is to determine how the NrfA protein responds to redox status in the microbial cells.

Effects of Plantation Type and Soil Depth on Microbial Community Structure and Nutrient Cycling Function.

Declining soil quality and microecological imbalances were evaluated in larch plantations in this study. One potential solution to this problem is the cultivation of mixed coniferous and broad-leaved plantations. However, it is unclear whether and how soil microbial community structure and nutrient cycling function would be affected by mixed plantations and soil depths. In this study, we used high-throughput sequencing technology to investigate bacterial 16S and fungal ITS regions for comparisons of soil microbial diversity among plantation types (a Larix gmelinii pure plantation, a Fraxinus mandshurica pure plantation, a Larix–Fraxinus mixed plantation within the Larix row, the Fraxinus row, and between the Larix and Fraxinus rows) and soil depths (0–10, 10–20, and 20–40 cm). These data were used to evaluate variations in microbial communities and nutrient cycling function with the determining environmental factors. Our results indicated that bacteria had a stronger spatial dependence than did fungi, while plantation types significantly affected the fungal community. The relative abundance of Gaiellaceae, as well as bacterial ligninolysis, nitrate ammonification, and nitrite ammonification functions significantly increased with increasing soil depth. Compared with other plantations, the relative abundance of Inocybaceae was significantly higher in the Larix plantation. Distance-based redundancy analysis (db-RDA) showed that Gaiellaceae and Inocybaceae abundances were positively correlated with ammonium nitrogen content, available phosphorus content, and phosphatase activity. Our findings indicate that variations in soil available phosphorus are closely related to the relative abundances of Gaiellaceae at different soil depths and Inocybaceae in different plantation types. Mixed plantations might change the availability of soil phosphorus by controlling the relative abundance of Inocybaceae. We recommend that fungal community changes be considered in the sustainable management of mixed plantations.

Plume Layer Influences the Amazon Reef Sponge Microbiome Primary Producers

Symbiont relationships between corals and photosynthetic microorganisms sustain coral reef existence. However, the Great Amazon Reef System (GARS) stays under a plume layer that attenuates the entry of light, and instead of corals, sponges are the major reef epifauna, for which little is known about the function of the associated microbiome. Here, we used genome-resolved metagenomics to investigate how the sponge microbiome supports its host and overcomes the reduced light availability, recovering 205 MAGs from Agelas and Geodia sponges with completeness &amp;gt;70% and contamination &amp;lt;10%. Beta diversity estimates based on the 16S rRNA genes indicated the microbiomes of Amazon and Caribbean sponges to be distinct (P&amp;lt;0.01), with heterotrophic lifestyles being prevalent in Amazon sponge microbiomes (P&amp;lt;0.05). Nevertheless, genes indicating the carbon fixation pathways 3-Hydroxypropionate/4-Hydroxybutyrate cycle, 3-Hydroxypropionate bicycle, Reductive Tricarboxylic Acid Cycle, and Calvin-Benson-Bassham cycle could be recovered in low abundance. The presence of Cyanobacteria, represented by both 16S rRNA analyses and low-quality MAGs indicated light incidence on the reef. The metabolic profile shows that the GARS sponge microbiome had genes for sulfate reduction, sulfur oxidation, nitric oxide reduction, ammonia oxidation, nitrate reduction, nitrite ammonification, nitrite oxidation, and nitrite reduction, indicating that the microbiome might play a role in detoxification of the holobiont. We conclude, that neither the plume-limited photosynthesis of the sponge microbiome nor the primary producers sustain the organic carbon input for the sponges, which likely live off plume-associated organic carbon and their heterotrophic microbiota.

Comparison of the combustion and emission characteristics of NH3/NH4NO2 and NH3/H2 in a two-stroke low speed marine engine

As a marine engine fuel of great concern, ammonia needs to be mixed with another high reactive fuel to improve its combustion performance. In this work, the combustion performance of NH3/NH4NO2 and NH3/H2 was compared under different boundary conditions (excess air coefficient, initial temperature, pressure and mixing ratio). The numerical simulation of compression combustion is carried out under different power loads. The addition of ammonium nitrite decreases the ignition requirement of ammonia and shortens the ignition delay time of the mixture fuel. The boundary conditions of compression ignition can be reduced by mixing hydrogen and mixing ammonium nitrite, but it is not enough to achieve compression ignition under NH3/H2 mode. The addition of 30% ammonium nitrite can reduce the intake temperature to 300–360 K, which makes the compression ignition of the mixed fuel feasible. Meanwhile, in order to reduce the high in-cylinder combustion pressure and improve the combustion performance of the mixed fuel, the fuel injection strategy was proposed to achieve constant combustion pressure of 30 MPa under the premise of less power loss, which is a potential solution for the combustion of ammonia fuel.

THE PROBLEM OF WATER INTAKE SOURCES AS A CONSEQUENCE OF EUTROPHICATION AND WATER SHORTAGE AND POLLUTION OF COMMUNAL AND AGRICULTURAL ORIGIN

It was investigated that the ecological condition of the Verkhnie Ivachiv water intake complex is determined by physicochemical, hydrological, biological (eutrophication), climatic (overdrying and water shortage), and anthropic (pollution) factors. Biogenic accumulation of nitrogen, phosphorus, and heavy metal compounds was detected in the process of water purification. The main problem of water quality in the Verkhnie Ivachiv water intake is rainwater runoff from the shores and the activities of the Malashiv landfill. It is established that the main factor influencing the surface water quality of Verkhnie Ivachiv reservoir is agriculture, which is manifested in the stable presence of ammonium nitrogen, nitrate and nitrite ions, increased biochemical oxygen consumption. Water quality is also significantly affected by anthropogenic pollution factors, primarily sewage from the Malashiv landfill, agricultural washout, disposal of organic matter, etc.

Vegetation and water of lowland spring-wells in Po Plain (Northern Italy): ecological features and management proposals

Spring-wells (lowland springs, “fontanili”) are elements of Po Plain (Northern Italy) with ecological and historical importance. There, spring-water flows naturally and rises to the surface at a relatively constant temperature, generating unique ecosystems dependent on the groundwater outflow. Despite their importance, they are endangered by degradation processes as the expansion of urban areas and/or the intensification of agriculture, very marked in Po Plain. This research describes four spring-wells of Po Plain from a botanical and ecological perspective through phytosociological relevés and different ecological indexes. Water chemical-physical features are also considered (pH, temperature and ammonium ion, nitrite, nitrate, orthophosphate, chloride and organic matters contents). Plant communities of the spring-well beds show a low number of species (5.8 ± 2.9) but also no exotic species while the vegetation of the banks has a high number of species (32.4 ± 9.8) but several of them are exotic/ornamental. The low value of the Ecological Index of Maturity of the vegetation of the banks (EIM = 4.4 ± 1.5) indicate disturbances, however moderate compared to the surrounding corn fields (EIM ~ 0). All the water samples has high ammonium content (> 0.50 ppm), the water of the spring-well B results the most polluted and both algae and Callitriche obtusangula (rare native species) grow largely in it, while spring-well C has less phosphates and more nitrite and is marked by Equisetum telmateia. Management proposals to protect and enhance the studied spring-wells, as the gradual removal of exotic species and the planting of native species, are discussed.

Agricultural practices of perennial energy crops affect nitrogen cycling microbial communities

Production of perennial bioenergy crops on farmland that is suboptimal for food crops may mitigate nitrous oxide emissions and reduce nutrient loss while producing bioenergy feedstocks. The ability of bioenergy crops to provide these multiple ecosystem services depends on interactions between the soil N cycle and the bioenergy production system, but our understanding of these interactions is limited. The objective of this study was to determine the effects of perennial energy crop management practices, including grass species (switchgrass, prairie cordgrass, Miscanthus × giganteus, and a grass mixture), harvest timing (at anthesis and after a killing frost), and N application rate (0, 56, and 112 kg N ha−1) on populations of N-cycling soil microorganisms. We quantified the abundances of genes encoding N cycling enzymes involved in ammonia oxidation (amoA), nitrite ammonification (nrfA), denitrification (nirK, nirS, norB, and nosZ), and N fixation (nifH). We found that N application significantly affected the abundance of N-cycling genes. The abundance of bacterial amoA (AOB) increased as N fertilization increased, thereby increasing the proportion of AOB compared to archaeal amoA (AOA). The nitrite reductase genes, nrfA and nirS, were more abundant in the plots with 56 kg N ha−1 applied; however, the nirK nitrite reductase did not differ across N applications. Overall, AOA, nrfA, and norB were correlated with each other as were AOB, nirK, and nosZ. Our data imply that management practices of perennial grasses, especially N application, could have significant impacts on functionally important soil microbial communities within the soil.

The Structure and Function of Gut Microbiomes of Two Species of Sea Urchins, Mesocentrotus nudus and Strongylocentrotus intermedius, in Japan

Sea urchin is an indicator of coastal environmental changes in the global warming era, and is also a model organism in developmental biology and evolution. Due to the depletion of wild resources, new aquaculture techniques for improving stocks have been well studied. The gut microbiome shapes various aspects of a host’s physiology. However, these microbiome structures and functions on sea urchins, particularly Mesocentrotus nudus and Strongylocentrotus intermedius which are important marine bioresources commonly found in Japan, have not been fully investigated yet. Using metagenomic approaches including meta16S and shotgun metagenome sequencings, the structures, functions, and dynamics of the gut microbiome of M. nudus and S. intermedius, related to both habitat environment and host growth, were studied. Firstly, a broad meta16S analysis revealed that at the family level, Psychromonadaceae and Flavobacteriaceae reads (38–71%) dominated in these sea urchins, which is a unique feature observed in species in Japan. Flavobacteriaceae reads were more abundant in individuals after rearing in an aquarium with circulating compared to one with running water. Campylobacteraceae and Vibrionaceae abundances increased in both kinds of laboratory-reared sea urchins in both types of experiments. 2-weeks feeding experiments of M. nudus and S. intermedius transplanted from the farm to laboratory revealed that these gut microbial structures were affected by diet rather than rearing environments and host species. Secondly, further meta16S analysis of microbial reads related to M. nudus growth revealed that at least four Amplicon Sequence Variant (ASV) affiliated to Saccharicrinis fermentans, which is known to be a nitrogen (N2) fixing bacterium, showed a significant positive correlation to the body weight and test diameter. Interestingly, gut microbiome comparisons using shotgun metagenome sequencing of individuals showing higher and lower growth rates revealed a significant abundance of “Nitrate and nitrite ammonification” genes in the higher-grown individuals under the circulating water rearing. These findings provide new insights on the structure-function relationship of sea urchin gut microbiomes beyond previously reported nitrogen fixation function in sea urchin in 1950s; we discovered a nitrate reduction function into ammonium for the growth promotion of sea urchin.