Enhancement of nitrogen and phosphorus removal from eutrophic water by economic plant annual ryegrass (Lolium multiflorum) with ion implantation

Technologies for performance intensification of floating treatment wetland - An explicit and comprehensive review

With the wide application of floating treatment wetland (FTW), the limited performance of FTWs should be improved. A comprehensive review is accordingly necessary to summarize the state-of-the-art on FTWs for performance improvement. An attempt has been made to gain information from literature about technologies to enhance the performance of FTWs. These technologies have been classified into three categories according to their mechanisms: 1) increasing the amount and activity of bacteria; 2) enhancing the growth of plant; and 3) configurable innovations. The design and application of each enhanced FTW have been discussed in detail. Thereafter, all the technologies have been compared and analyzed according to their improvement in pollutant removal and ecological effects. In summary, FTW with additional bio-carriers has a higher potential for future applications with the benefits of wide application conditions, scale-up potential, and the easy combination with other methods to further improve the removal efficiency. The stability and sustainability of these technologies should be further investigated.

The Relevance of Host Gut Microbiome Signature Alterations on de novo Fatty Acids Synthesis in Patients with Multi-Drug Resistant Tuberculosis

Background

Tuberculosis (TB) is still the single pathogen infectious disease with the largest number of deaths worldwide. The relationship that intestinal microbiota disorder and de novo fatty acid synthesis metabolism have with disease progression in multi-drug resistant TB (MDR-TB) has not yet been fully studied.

Objective

To investigate the effects of long periods of MDR-TB, pre-extensively drug-resistant TB (pre-XDR-TB), or rifampicin-resistant TB (RR-TB) on gut microbiome dysbiosis and advanced disease.

Methods

The sample was chosen between March 2019 and September 2019 in Wenzhou Central Hospital and comprised 11 patients with pre-XDR-TB, 23 patients with RR-TB, and 28 patients with MDR-TB. Healthy individuals were chosen as the control group (CK group). An overnight fast blood sample was drawn via venipuncture into tubes without anticoagulant. For analysis, 300 mg of faeces from patients from the same group was mixed and analysed using DNA extraction, NGS sequencing, and bioinformatics. A QIAamp Fecal DNA Mini Kit was used to isolate the DNA. The extracted DNA was stored at -20°C.

Results

Advanced TB was concurrent with an elevated level of the proportions of acetyl-CoA carboxylase (ACC1) to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and fatty acid synthase (FASN) to GAPDH in de novo fatty acids synthesis, and Eubacterium, Faecalibacterium, Roseburia, and Ruminococcus were increased significantly in RR-TB patients compared to healthy individuals, whereas their abundance in the pre-XDR-TB and MDR-TB groups showed little change in comparison with the control group. Proteobacteria levels were greatly increased in the RR-TB and MDR-TB patient groups but not in the patients with pre-XDR-TB or the healthy subjects. The pre-XDR-TB group exhibited alterations of the intestinal microbiome: coliform flora showed the highest abundance of Verrucomicrobiales, Enterobacteriales, Bifidobacteriales and Lactobacillales. De novo fatty acids synthesis was enhanced in patients and was associated with the gut microbiome dysbiosis induced by the antimicrobials, with Bacteroidetes, Bacteroidales, and Bacteroidaceae displaying the most important correlations on a phylum, order, and family level, respectively.

Conclusion

The progression to advanced TB was observed to be a result of the interaction between multiple interrelated pathways, with gut-lung crosstalk potentially playing a role in patients with drug-resistant TB.

Treating carbon-limited wastewater by DWTR and woodchip augmented floating constructed wetlands

Floating constructed wetlands (FCWs) have attained tremendous popularity for water purification purposes. However, FCW functions establishment in nutrients removal from carbon-limited wastewater, especially in cold weather, is still a challenge. Here, two drinking water treatment residual (DWTR) based biocarriers (B-I: DWTR cakes, B-II: DWTR cakes combined with woodchips) have been augmented into FCW to enhance the nutrients (N and P) removal performance. Compared to the traditional FCW, the intensified FCWs simultaneously achieved higher N and P removal efficiencies, with average pollutants removal of 52.16 ± 11.51% for TN and 92.72 ± 1.61% for TP in FCW-I and 57.65 ± 9.43% for TN and 92.17 ± 2.55% for TP in FCW-II, respectively, while their removal in FCW-III of 27.74 ± 7.11% for TN and 17.91 ± 9.27% for TP. B-II performed best in overcoming the negative influence of low temperature in nutrients removal. Mass balance budget indicated that most P was enriched in DWTR based biocarriers. Thus it is feasible to recycle and recover P from the surface water. Furthermore, P in the sediment can be changed from active P to stable P, mitigating the internal P release risk. This study can help to expand the understanding of the intensified FCWs and promote the practical application of FCWs.

Effects of high levels of nitrogen and phosphorus on perennial ryegrass (Lolium perenne L.) and its potential in bioremediation of highly eutrophic water

The conservation and management of rain and water in a city environment are a crucial aspect of sustainability. Sponge cities are a solution for the remediation of excessive water consumption, high pollution, and rainstorm waterlogging in urban areas. Perennial ryegrass (Lolium perenne L.) is a common species and promising bioremediation plant for the construction of sponge cities. It could be useful to purify high nitrogen and phosphorus content in wastewater runoff, but its response to high total nitrogen (TN) and total phosphorus (TP) levels has not been studied. The present study aimed to evaluate the effects of high TN + TP level on seed germination, plant growth, antioxidant response, and assimilation rate of N and P in perennial ryegrass. Compared with the control, treatments with 20 mg/L N + 4 mg/L P (20N4P) significantly decreased germination potential at day 3, but the germination rate at day 10 was similar between all treatments and the control, suggesting that a high TN + TP concentration might delay germination, but not prevent it. Treatment with 20N4P also induced significant withering and decreased shoot length, root length, and dry shoot weight of ryegrass seedlings, compared with the control. Treatments with 80N16P significantly decreased levels of chlorophyll a (Chl-a) and chlorophyll b (Chl-b), demonstrating inhibition of photosynthesis. Compared with the control, treatment with 40N8P increased the carotenoid (Car), malondialdehyde (MDA), and glutathione (GSH) content, which might alleviate oxidative stress induced by high TN + TP concentration. Moreover, high levels of TN + TP (160N32P and 320N64P) significantly reduced the removal capacity of N and P by plants. Overall, the present results provide a theoretical foundation for the development of ryegrass for bioremediation of wastewater during construction of sponge cities.

A New Type of Ecological Floating Bed Based on Ornamental Plants Experimented in an Artificially Made Eutrophic Water Body in the Laboratory for Nutrient Removal

In this study, a new type of ecological floating bed (NT-EFB) employing ornamental plants (either Spathiphyllum floribundum, Hydrocotyle sibthorpioids, Chlorophytum comosum or Peperomia obtusifolia) was designed to purify confected eutrophic water for 39 days. The growth characteristics of the plants and the effect of water treatment were analyzed and compared. The results showed that: (1) all the four ornamental plants examined survived well in the eutrophic water and an increase of plant biomass was observed; (2) the degradation efficiency of TOC by adding plants was about 85.0%; (3) the removal rate of NH₄⁺-N was about 97.0%; (4) all the four plants can be used as floating bed plants to treat eutrophic water and Hydrocotyle sibthorpioids had the best growth characteristics and treatment efficiency. The study provides an adequate reference for the treatment of eutrophication using ecological floating beds.

Adjustment of Photosynthetic and Antioxidant Activities to Water Deficit Is Crucial in the Drought Tolerance of Lolium multiflorum/Festuca arundinacea Introgression Forms

Lolium multiflorum/Festuca arundinacea introgression forms have been proved several times to be good models to identify key components of grass metabolism involved in the mechanisms of tolerance to water deficit. Here, for the first time, a relationship between photosynthetic and antioxidant capacities with respect to drought tolerance of these forms was analyzed in detail. Two closely related L. multiflorum/F. arundinacea introgression forms distinct in their ability to re-grow after cessation of prolonged water deficit in the field were selected and subjected to short-term drought in pots to dissect precisely mechanisms of drought tolerance in this group of plants. The studies revealed that the form with higher drought tolerance was characterized by earlier and higher accumulation of abscisic acid, more stable cellular membranes, and more balanced reactive oxygen species metabolism associated with a higher capacity of the antioxidant system under drought conditions. On the other hand, both introgression forms revealed the same levels of stomatal conductance, CO₂ assimilation, and consequently, intrinsic water use efficiency under drought and recovery conditions. However, simultaneous higher adjustment of the Calvin cycle to water deficit and reduced CO₂ availability, with respect to the accumulation and activity of plastid fructose-1,6-bisphosphate aldolase, were clearly visible in the form with higher drought tolerance.

An innovative lanthanum carbonate grafted microfibrous composite for phosphate adsorption in wastewater

Excessive presence of phosphorus in waters can cause eutrophication, a global unsolved environmental problem that has caused harmful effects to our eco-system and the source of our drinking water. In the study presented in this paper, a novel lanthanum carbonate grafted microfibrous composite (LC-MC) adsorbent was synthesized aiming at removing large amount of phosphate in wastewater efficiently. An optimized LC-MC was firstly prepared. The most suitable pH for the phosphate uptake was pH 7 to 9. The adsorption showed similar behavior in a wide range of ionic strength. The presence of co-existing anions was proved to have a less significant effect on the removal. The adsorption isotherm data were better fitted by the Freundlich isotherm than the Langmuir isotherm. The equilibrium was reached at about 300 min of contact time. 80 % of original adsorption capacity can be achieved even after 5 cycles of adsorption- desorption operations, indicating great regenerative performance of the adsorbent. The adsorption mechanism study showed that the ligand exchange played a key role during the phosphate adsorption.

Exploration of an urban lake management model to simulate chlorine interference based on the ecological relationships among aquatic species

In eutrophic lakes, algae are known to be sensitive to chlorine, but the impact of chlorine on the wider ecosystem has not been investigated. To quantitatively investigate the effects of chlorine on the urban lake ecosystem and analyze the changes in the aquatic ecosystem structure, a dynamic response model of aquatic species to chlorine was constructed based on the biomass density dynamics of aquatic species of submerged macrophytes, phytoplankton, zooplankton, periphyton, and benthos. The parameters were calibrated using data from the literature and two simulative experiments. The model was then validated using field data from an urban lake with a surface area of approximately 8000 m² located in the downtown area of Guangzhou, South China. The correlation coefficient (R), root mean square error-observations standard deviation ratio (RSR) and index of agreement (IOA) were used to evaluate the accuracy and reliability of the model and the results were consistent with the observations (0.446 R < 0.985, RSR < 0.7, IOA > 0.6). Comparisons between the simulated and observed trends confirmed the feasibility of using this model to investigate the dynamics of aquatic species under chlorine interference. The model can help managers apply a modest amount of chlorine to control eutrophication and provides scientific support for the management of urban lakes.

P uptake characteristics and root morphological responses in the mining ecotype of Polygonum hydropiper under high organic P media

Understanding plant phosphorus (P) assimilation and its root morphological responses is important to acquire an ideal material for remediation of P-enriched environments. Pot experiments were conducted to explore P accumulation and root morphological traits in a mining ecotype (ME) and non-mining ecotype (NME) of Polygonum hydropiper under different organic P (Po) sources (G1P, AMP, ATP, IHP) and inorganic P (Pi) source (KH₂PO₄), and also their responses to a high level of IHP for different growth periods. Both ecotypes showed higher biomass in Pi and IHP treatments than other Po sources. P accumulation in seedlings were in the order of Pi > IHP > other Po media. Extending the growth period increased biomass and P accumulation in both ecotypes. The ME demonstrated 1.11-1.46 times higher P accumulation than the NME. Seedlings fed with IHP demonstrated significantly greater morphological parameters of fine, medium, and thick roots compared to other Po sources. Total root length, surface area, and volume of both ecotypes significantly increased with the prolonged growth period. The ME has a higher ability to develop root system and exhibits better distribution of fine roots to enhance P accumulation from high P media, and thus it is a worthy material for P-phytoextraction.

The Impact of Phosphorus Supply on Selenium Uptake During Hydroponics Experiment of Winter Wheat (Triticum aestivum) in China

Selenium (Se) is a necessary trace element for humans and animals, and Se fertilization is an efficient way to increase Se concentration in the edible parts of crops, thus enhance the beneficiary effects of Se in human and animal health. Due to the similarity of physical and chemical properties between phosphate () and selenite (), phosphorus (P) supply often significantly impacts the absorption of Se in plants, but little is known about how P supply influences the subcellular distribution and chemical forms of Se. In this study, the effects of P supply on subcellular distribution and chemical forms of Se in winter wheat were investigated in a hydroponic trial with medium Se level (0.1 mg Se L-1). P was applied with three concentrations (0.31, 3.1, and 31 mg P L-1) in the experiment. The results showed that increasing P supply significantly decreased the concentration and accumulation of Se in the roots, stems, and leaves of winter wheat. An increase in P supply significantly inhibited Se accumulation in the root cell wall, but enhanced Se distribution in the organelles and soluble fraction of root cells. These findings suggest that increased P supply inhibited the root-to-shoot transport of Se. An increase in P supply enhanced Se accumulation in the cell wall of plant stems (both apical and axillary stem) and cell organelles of plants leaves, but inhibited Se distribution in the soluble fraction of stems and leaves. This suggests that P supply enhances Se transportation across the cell membrane in shoots of winter wheat. In addition, increased P supply also altered the chemical forms of Se in tissues of winter wheat. These findings will help in understanding of the regulation grain Se accumulation and provide a practical way to enhance Se intake for humans inform Se-enriched grains.

Integrated omics data of two annual ryegrass (Lolium multiflorum L.) genotypes reveals core metabolic processes under drought stress

BACKGROUND

Annual ryegrass (Lolium multiflorum L.) is a commercially important, widely distributed forage crop that is used in the production of hay and silage worldwide. Drought has been a severe environmental constraint in its production. Nevertheless, only a handful of studies have examined the impact of short-term drought stress on annual ryegrass. The aim of this study was to explore how stress-induced core metabolic processes enhance drought tolerance, or adaptation to drought, in annual ryegrass.

RESULTS

We profiled the transcriptomes, proteomes, and metabolomes of two annual ryegrass genotypes: the drought-resistant genotype "Abundant 10" and drought-susceptible genotype "Adrenalin 11." We identified differentially expressed metabolites and their corresponding proteins and transcripts that are involved in 23 core metabolic processes, in response to short-term drought stress. Protein-gene-metabolite correlation networks were built to reveal the relationships between the expression of transcripts, proteins, and metabolites in drought-resistant annual ryegrass. Furthermore, integrated metabolic pathways were used to observe changes in enzymes corresponding with levels of amino acids, lipids, carbohydrate conjugates, nucleosides, alkaloids and their derivatives, and pyridines and their derivatives. The resulting omics data underscored the significance of 23 core metabolic processes on the enhancement of drought tolerance or adaptation to drought in annual ryegrass.

CONCLUSIONS

The regulatory networks were inferred using MCoA and correlation analysis to reveal the relationships among the expression of transcripts, proteins, and metabolites that highlight the corresponding elements of these core metabolic pathways. Our results provide valuable insight into the molecular mechanisms of drought resistance, and represent a promising strategy toward the improvement of drought tolerance in annual ryegrass.

An endophytic microbe from an unusual volcanic swamp corn seeks and inhabits root hair cells to extract rock phosphate

In the animal microbiome, localization of microbes to specific cell types is well established, but there are few such examples within the plant microbiome which includes endophytes. Endophytes are non-pathogenic microbes that inhabit plants. Root hairs are single cells, equivalent to the nutrient-absorbing intestinal microvilli of animals, used by plants to increase the root surface area for nutrient extraction from soil including phosphorus (P). There has been significant interest in the microbiome of intestinal microvilli but less is known about the root hair microbiome. Here we describe a bacterial endophyte (3F11) from Zea nicaraguensis, a wild corn discovered in a Nicaraguan swamp above rock-P lava flowing from the San Cristobal volcano. Rock-P is insoluble and a major challenge for plants. Following seed coating and germination on insoluble-P, the endophyte colonized epidermal surfaces, ultimately colonizing root hairs intracellularly. The endophyte promoted root hair growth and secreted acids to solubilize rock-P for uptake by a larger root hair surface. The most interesting observation was that a seed-coated endophyte targeted and colonized a critical cell type, root hair cells, consistent with earlier studies. The endophyte maintained its targeting ability in two evolutionary divergent hosts, suggesting that the host recognition machinery is conserved.

Growth characteristics and nutrient removal capability of eco-ditch plants in mesocosm sediment receiving primary domestic wastewater

Eco-ditches are being explored to maximize their capability of capturing pollutants and mitigate any harmful side effects in rivers. In this study, mesocosm plastic drum sediment and field experiments were set up to screen 18 plant species found in ditches and identify those with potential for high biomass production and nutrients removal. Terrestrial plants grown in the mesocosm system were shown to be able to acclimate to aquatic conditions and to survive in primary domestic sewage. About 73-95% increase in plant biomass was recorded. Removal efficiencies for total nitrogen, total phosphorus, and ammonium-nitrogen from the sewage of 72-99%, 64-99%, and 75-100%, respectively, were recorded. Furthermore, complete removal of the applied nitrate-nitrogen load was achieved in mesocosm systems. Findings also show that all species, but especially Acorus calamus, Canna indica, Canna lily, Cyperus alternifolius, Colocasia gigantea, Eichhornia crassipes, Iris sibirica, and Typha latifolia had the highest efficiencies for nitrogen and phosphorous removal. The N and P mass balance analysis demonstrated that plant uptake and sediment N and P accumulation accounted for 41-86% and 18-49% of the total influent TN and TP loads, respectively. In addition, the amounts of nitrogen and phosphorous uptake by these plant species were influenced significantly by biomass. The field-culture experiment further identified Canna indica followed by Cyperus alternifolius as the most promising for high biomass production and nutrients uptake. Therefore, these plants may be recommended for extensive use in treating highly eutrophicated rivers. Outcomes of this work can be useful for model design specifications in eco-ditch mitigation of sewage pollution.

Assessing the influence of different plant species in drainage ditches on mitigation of non-point source pollutants (N, P, and sediments) in the Purple Sichuan Basin

Three different types of ditches, each 300 m in length, were employed in this study. One vegetated constructed ditch (VCD), three natural vegetated soil ditches (NVSD), and three constructed ditches left unvegetated (UCD) as controls were investigated using simple in/out mass balances and uptake by plant species with a potential for phytoremediation and their mechanisms. Significant differences in the ditches were observed, suggesting the importance of plant species in nutrient mitigation. The removal rates of TN (total nitrogen) and TP (total phosphorus) were 64.28 and 58.02, 31.16 and 27.49, and 3.91 and 2.97%, respectively, in the VCD, NVSD, and UCD. Canna indica (45.12 g m^-2) and Oenanthe javanica (21.48 g m^-2) had the highest total N and P storage in the VCD and NVSD. Furthermore, species C. indica possessed the highest annual N and P uptake in the VCD (216.59 kg N/ha/yr and 30.73 kg P/ha/yr). In the NVSD, species O. javanica had the greatest annual N and P uptake (96.66 kg N/ha/yr and 7.94 kg P/ha/yr). Both VCD and NVSD were found to have a reasonably good outcome compared to UCD. Retention of nutrients by ditch sediments was probably the major attenuation mechanism, with subsequent plant uptake and microbial nitrification-denitrification of the nutrients as secondary removal mechanisms. Results of this study highlight the importance of taking actions for establishment of appropriate plant species inside the ditches in order to enhance its direct and indirect roles and maximize purification rate in aquatic environments.

CeO2-covered nanofiber for highly efficient removal of phosphorus from aqueous solution

The lowering phosphorus concentration of lakes or rivers using adsorbents has been considered to be the most effective way to prevent water eutrophication. However, the development of an adsorbent is still challenging because conventional adsorbents have not shown a sufficient phosphorus adsorption capacity (0.3-2.0mmol/g) to treat industrial, agricultural or domestic wastewater at a large scale. Herein, a novel and effective strategy to remove phosphorus efficiently with a CeO2-covered nanofiber is shown. The CeO2-covered nanofiber was synthesized through (1) amine group immobilization onto an electrospun polyacrylonitrile nanofiber and (2) adsorption of Ce(3+) on it. The CeO2-covered nanofiber played a role in catching phosphate ions in an aqueous solution by the oxidation, reduction, and ion-exchange of adsorbed Ce(3+) on the nanofiber from CeO2 to CePO4, and enabled remarkable phosphate adsorption capacity of the nanofiber (ca. 17.0mmol/g) at the range of ca. pH 2-6. Our strategy might be the most feasible method to efficiently lower the phosphorus concentration in lakes or rivers owing to the easy and inexpensive preparation of CeO2-covered nanofiber at an industrial scale, with a high phosphate adsorption capacity.

Growth and efficiency of nutrient removal by Salix jiangsuensis J172 for phytoremediation of urban wastewater

Willows are a group of versatile tree species that may have multiple environmental applications. In the present study, Salix jiangsuensis J172 plants were grown in the fixed mats as an economic plant-based treatment system to evaluate its potential for removing nutrients in wastewater. Plants grew normally in wastewater compared with those in Hoagland solution. However, wastewater containing a high concentration of chlorine ions was toxic to S. jiangsuensis J172 plants. The plants accumulated large amounts of nitrogen and phosphorus in aboveground tissues under conditions of abundant supply. The removal efficiency for raw wastewater was 82.18-87.78 % for nitrogen, 57.35-65.58 % for phosphorus, and 58.24-59.90 % for chemical oxygen demand. Nutrient removal efficiency was positively correlated with the initial nutrient supply. The results show that S. jiangsuensis J172 grown in the fixed mat economic plant-based treatment system with nutrient-rich, eutrophic water may be an effective, low-cost phytoremediation technology to treat water containing undesirable levels of wastewater.

P accumulation and physiological responses to different high P regimes in Polygonum hydropiper for understanding a P-phytoremediation strategy

Phosphorus (P) accumulators used for phytoremediation vary in their potential to acquire P from different high P regimes. Growth and P accumulation in Polygonum hydropiper were both dependent on an increasing level of IHP (1–8 mM P) and on a prolonged growth period (3-9 weeks), and those of the mining ecotype (ME) were higher than the non-mining ecotype (NME). Biomass increments in root, stem, and leaf of both ecotypes were significantly greater in IHP relative to other organic P (Po) sources (G1P, AMP, ATP), but lower than those in inorganic P (Pi) treatment (KH₂PO₄). P accumulation in the ME exceeded the NME from different P regimes. The ME demonstrated higher root activity compared to the NME grown in various P sources. Acid phosphatase (Apase) and phytase activities in root extracts of both ecotypes grown in IHP were comparable to that in Pi, or even higher in IHP. Higher secreted Apase and phytase activities were detected in the ME treated with different P sources relative to the NME. Therefore, the ME demonstrates higher P-uptake efficiency and it is a potential material for phytoextraction from P contaminated areas, irrespective of Pi or Po contamination.