scholarly journals Engineered Root Bacteria Release Plant-Available Phosphate from Phytate

2019 ◽  
Vol 85 (18) ◽  
Author(s):  
Christine N. Shulse ◽  
Mansi Chovatia ◽  
Carolyn Agosto ◽  
Gaoyan Wang ◽  
Matthew Hamilton ◽  
...  
Keyword(s):  
High Yield ◽  
Natural Soil ◽  
Soluble Phosphate ◽  
Phosphate Fertilizers ◽  
Content Type ◽  
Generate Plant ◽  
Phytate Hydrolysis ◽  
Phosphate Solubilizing ◽  
Phosphate Source ◽  
Available Phosphate

ABSTRACTMicroorganisms that release plant-available phosphate from natural soil phosphate stores may serve as biological alternatives to costly and environmentally damaging phosphate fertilizers. To explore this possibility, we engineered a collection of root bacteria to release plant-available orthophosphate from phytate, an abundant phosphate source in many soils. We identified 82 phylogenetically diverse phytase genes, refactored their sequences for optimal expression inProteobacteria, and then synthesized and engineered them into the genomes of three root-colonizing bacteria. Liquid culture assays revealed 41 engineered strains with high levels of phytate hydrolysis. Among these, we identified 12 strains across three bacterial hosts that confer a growth advantage on the model plantArabidopsis thalianawhen phytate is the sole phosphate source. These data demonstrate that DNA synthesis approaches can be used to generate plant-associated strains with novel phosphate-solubilizing capabilities.IMPORTANCEPhosphate fertilizers are essential for high-yield agriculture yet are costly and environmentally damaging. Microbes that release soluble phosphate from naturally occurring sources in the soil are appealing, as they may reduce the need for such fertilizers. In this study, we used synthetic biology approaches to create a collection of engineered root-associated microbes with the ability to release phosphate from phytate. We demonstrate that these strains improve plant growth under phosphorus-limited conditions. This represents a first step in the development of phosphate-mining bacteria for future use in crop systems.

scholarly journals Inorganic Phosphate Solubilization by Rhizosphere Bacterium Paenibacillus sonchi: Gene Expression and Physiological Functions

2020 ◽  
Vol 11 ◽  
Author(s):  
Luciana F. Brito ◽  
Marina Gil López ◽  
Lucas Straube ◽  
Luciane M. P. Passaglia ◽  
Volker F. Wendisch
Keyword(s):  
Gene Expression ◽  
Organic Acids ◽  
Phosphate Solubilization ◽  
Tricarboxylic Acid Cycle ◽  
Initial Step ◽  
High Rate ◽  
Soluble Phosphate ◽  
Phosphate Solubilizing Bacteria ◽  
Phosphate Solubilizing ◽  
Phosphate Source

Due to the importance of phosphorus (P) in agriculture, crop inoculation with phosphate-solubilizing bacteria is a relevant subject of study. Paenibacillus sonchi genomovar Riograndensis SBR5 is a promising candidate for crop inoculation, as it can fix nitrogen and excrete ammonium at a remarkably high rate. However, its trait of phosphate solubilization (PS) has not yet been studied in detail. Here, differential gene expression and functional analyses were performed to characterize PS in this bacterium. SBR5 was cultivated with two distinct P sources: NaH2PO4 as soluble phosphate source (SPi) and hydroxyapatite as insoluble phosphate source (IPi). Total RNA of SBR5 cultivated in those two conditions was isolated and sequenced, and bacterial growth and product formation were monitored. In the IPi medium, the expression of 68 genes was upregulated, whereas 100 genes were downregulated. Among those, genes involved in carbon metabolism, including those coding for subunits of 2-oxoglutarate dehydrogenase, were identified. Quantitation of organic acids showed that the production of tricarboxylic acid cycle-derived organic acids was reduced in IPi condition, whereas acetate and gluconate were overproduced. Increased concentrations of proline, trehalose, and glycine betaine revealed active osmoprotection during growth in IPi. The cultivation with hydroxyapatite also caused the reduction in the motility of SBR5 cells as a response to Pi depletion at the beginning of its growth. SBR5 was able to solubilize hydroxyapatite, which suggests that this organism is a promising phosphate-solubilizing bacterium. Our findings are the initial step in the elucidation of the PS process in P. sonchi SBR5 and will be a valuable groundwork for further studies of this organism as a plant growth-promoting rhizobacterium.

SEC permits abbreviated tender and exchange offers for non-convertible high-yield and investment-grade debt securities

2015 ◽  
Vol 16 (3) ◽  
pp. 28-29
Author(s):  
Ian B. Blumenstein ◽  
J. Eric Maki ◽  
John T. Owen
Keyword(s):  
Design Methodology ◽  
High Yield ◽  
Content Type ◽  
Efficient Mechanism ◽  
Practical Guidance ◽  
Traditional Structures ◽  
Investment Grade ◽  
Practical Implications

Purpose – To advise companies of a recent SEC no-action letter relating to tender and exchange offers for certain debt securities. Design/methodology/approach – Reviews various conditions allowing an issuer to use a shortened timeframe in which certain debt tender/exchange offers need be kept open for as few as five business days. Findings – The abbreviated debt tender/exchange offer structure contemplated by the no-action letter provides a more efficient mechanism for conducting debt tender/exchange offers in certain circumstances. Practical implications – Issuers conducting a debt tender/exchange offer should consider whether the new abbreviated structure is more effective in achieving their objectives than the more traditional structures. Originality/value – Practical guidance from experienced securities regulatory lawyers that gives an overview of important developments in debt tender/exchange offer practice.

Microwave synthesis, photophysical properties of novel fluorescent iminocoumarins and their application in textile printing

2015 ◽  
Vol 44 (2) ◽  
pp. 87-93 ◽  
Author(s):  
G.H. Elgemeie ◽  
K.A. Ahmed ◽  
E.A. ahmed ◽  
M.H. helal ◽  
D.M. Masoud
Keyword(s):  
Blue Light ◽  
Microwave Synthesis ◽  
Photophysical Properties ◽  
Ethyl Cyanoacetate ◽  
High Yield ◽  
The Novel ◽  
Dioxane Solution ◽  
Content Type ◽  
Textile Printing ◽  
Short Time

Purpose – This paper aims to synthesise coumarine flourescent dyes from a cheap material in a very short time with a very high yield, and by using a clean green chemistry. Design/methodology/approach – Efficient microwave synthesis for some novel iminocoumarins starts from the reaction of p-phenyl-enediamine and ethyl cyanoacetate followed by cyclocondensation with salicylaldehyde derivatives. Findings – The synthesized iminocoumarine compounds were characterized by spectroscopic methods. Absorption and fluorescence spectra of the compounds were also recorded. All compounds were fluorescent in 1,4-dioxane solution, they all emitted blue light (440-460 nm). The printing properties were studied, and their applications on printing polyester and polyamide fabrics were studied by silk screen printing. Originality/value – The authors designed efficient microwavel synthesis for some novel iminocoumarine derivatives; The novel procedure features short-reaction time, moderate yields and simple workup; All compounds were fluorescent in 1,4-dioxane solution, and they all emitted blue light; The authors studied their application in printing polyester and polyamide fabrics.

scholarly journals Hyperthermophilic Carbamate Kinase Stability and Anabolic In Vitro Activity at Alkaline pH

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
James E. Hennessy ◽  
Melissa J. Latter ◽  
Somayeh Fazelinejad ◽  
Amy Philbrook ◽  
Daniel M. Bartkus ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hyperthermophilic Archaea ◽  
High Yield ◽  
Water Runoff ◽  
High Catalytic Activity ◽  
Alkaline Ph ◽  
Biotechnological Applications ◽  
Carbamoyl Phosphate ◽  
Content Type ◽  
Carbamate Kinase

ABSTRACT Carbamate kinases catalyze the conversion of carbamate to carbamoyl phosphate, which is readily transformed into other compounds. Carbamate forms spontaneously from ammonia and carbon dioxide in aqueous solutions, so the kinases have potential for sequestrative utilization of the latter compounds. Here, we compare seven carbamate kinases from mesophilic, thermophilic, and hyperthermophilic sources. In addition to the known enzymes from Enterococcus faecalis and Pyrococcus furiosus , the previously unreported enzymes from the hyperthermophiles Thermococcus sibiricus and Thermococcus barophilus , the thermophiles Fervidobacterium nodosum and Thermosipho melanesiensis , and the mesophile Clostridium tetani were all expressed recombinantly, each in high yield. Only the clostridial enzyme did not show catalysis. In direct assays of carbamate kinase activity, the three hyperthermophilic enzymes display higher specific activities at elevated temperatures, greater stability, and remarkable substrate turnover at alkaline pH (9.9 to 11.4). Thermococcus barophilus and Thermococcus sibiricus carbamate kinases were found to be the most active when the enzymes were tested at 80°C, and maintained activity over broad temperature and pH ranges. These robust thermococcal enzymes therefore represent ideal candidates for biotechnological applications involving aqueous ammonia solutions, since nonbuffered 0.0001 to 1.0 M solutions have pH values of approximately 9.8 to 11.8. As proof of concept, here we also show that carbamoyl phosphate produced by the Thermococcus barophilus kinase is efficiently converted in situ to carbamoyl aspartate by aspartate transcarbamoylase from the same source organism. Using acetyl phosphate to simultaneously recycle the kinase cofactor ATP, at pH 9.9 carbamoyl aspartate is produced in high yield and directly from solutions of ammonia, carbon dioxide, and aspartate. IMPORTANCE Much of the nitrogen in animal wastes and used in fertilizers is commonly lost as ammonia in water runoff, from which it must be removed to prevent downstream pollution and evolution of nitrogenous greenhouse gases. Since carbamate kinases transform ammonia and carbon dioxide to carbamoyl phosphate via carbamate, and carbamoyl phosphate may be converted into other valuable compounds, the kinases provide a route for useful sequestration of ammonia, as well as of carbon dioxide, another greenhouse gas. At the same time, recycling the ammonia in chemical synthesis reduces the need for its energy-intensive production. However, robust catalysts are required for such biotransformations. Here we show that carbamate kinases from hyperthermophilic archaea display remarkable stability and high catalytic activity across broad ranges of pH and temperature, making them promising candidates for biotechnological applications. We also show that carbamoyl phosphate produced by the kinases may be efficiently used to produce carbamoyl aspartate.

How to estimate expected credit losses – ECL – for provisioning under IFRS 9

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mariya Gubareva
Keyword(s):  
Risk Premium ◽  
Default Risk ◽  
Financial Regulation ◽  
Credit Default Swap ◽  
High Yield ◽  
Expected Loss ◽  
Content Type ◽  
Term Structures ◽  
Ifrs 9 ◽  
Investment Grade

PurposeThis paper provides an objective approach based on available market information capable of reducing subjectivity, inherently present in the process of expected loss provisioning under the IFRS 9.Design/methodology/approachThis paper develops the two-step methodology. Calibrating the Credit Default Swap (CDS)-implied default probabilities to the through-the-cycle default frequencies provides average weights of default component in the spread for each forward term. Then, the impairment provisions are calculated for a sample of investment grade and high yield obligors by distilling their pure default-risk term-structures from the respective term-structures of spreads. This research demonstrates how to estimate credit impairment allowances compliant with IFRS 9 framework.FindingsThis study finds that for both investment grade and high yield exposures, the weights of default component in the credit spreads always remain inferior to 33%. The research's outcomes contrast with several previous results stating that the default risk premium accounts at least for 40% of CDS spreads. The proposed methodology is applied to calculate IFRS 9 compliant provisions for a sample of investment grade and high yield obligors.Research limitations/implicationsMany issuers are not covered by individual Bloomberg valuation curves. However, the way to overcome this limitation is proposed.Practical implicationsThe proposed approach offers a clue for a better alignment of accounting practices, financial regulation and credit risk management, using expected loss metrics across diverse silos inside organizations. It encourages adopting the proposed methodology, illustrating its application to a set of bond exposures.Originality/valueNo previous research addresses impairment provisioning employing Bloomberg valuation curves. The study fills this gap.

scholarly journals Chromosome Engineering To Generate Plasmid-Free Phenylalanine- and Tyrosine-Overproducing Escherichia coli Strains That Can Be Applied in the Generation of Aromatic-Compound-Producing Bacteria

2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Daisuke Koma ◽  
Takahiro Kishida ◽  
Eisuke Yoshida ◽  
Hiroyuki Ohashi ◽  
Hayato Yamanaka ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Aromatic Compound ◽  
Aromatic Compounds ◽  
High Yield ◽  
Rational Approach ◽  
Chromosome Engineering ◽  
Phenyllactic Acid ◽  
Content Type ◽  
E Coli ◽  
Free Strains

ABSTRACT Many phenylalanine- and tyrosine-producing strains have used plasmid-based overexpression of pathway genes. The resulting strains achieved high titers and yields of phenylalanine and tyrosine. Chromosomally engineered, plasmid-free producers have shown lower titers and yields than plasmid-based strains, but the former are advantageous in terms of cultivation cost and public health/environmental risk. Therefore, we engineered here the Escherichia coli chromosome to create superior phenylalanine- and tyrosine-overproducing strains that did not depend on plasmid-based expression. Integration into the E. coli chromosome of two central metabolic pathway genes (ppsA and tktA) and eight shikimate pathway genes (aroA, aroB, aroC, aroD, aroE, aroGfbr, aroL, and pheAfbr), controlled by the T7lac promoter, resulted in excellent titers and yields of phenylalanine; the superscript “fbr” indicates that the enzyme encoded by the gene was feedback resistant. The generated strain could be changed to be a superior tyrosine-producing strain by replacing pheAfbr with tyrAfbr. A rational approach revealed that integration of seven genes (ppsA, tktA, aroA, aroB, aroC, aroGfbr, and pheAfbr) was necessary as the minimum gene set for high-yield phenylalanine production in E. coli MG1655 (tyrR, adhE, ldhA, pykF, pflDC, and ascF deletant). The phenylalanine- and tyrosine-producing strains were further applied to generate phenyllactic acid-, 4-hydroxyphenyllactic acid-, tyramine-, and tyrosol-producing strains; yield of these aromatic compounds increased proportionally to the increase in phenylalanine and tyrosine yields. IMPORTANCE Plasmid-free strains for aromatic compound production are desired in the aspect of industrial application. However, the yields of phenylalanine and tyrosine have been considerably lower in plasmid-free strains than in plasmid-based strains. The significance of this research is that we succeeded in generating superior plasmid-free phenylalanine- and tyrosine-producing strains by engineering the E. coli chromosome, which was comparable to that in plasmid-based strains. The generated strains have a potential to generate superior strains for the production of aromatic compounds. Actually, we demonstrated that four kinds of aromatic compounds could be produced from glucose with high yields (e.g., 0.28 g tyrosol/g glucose).

scholarly journals Complete Genome Sequence of Burkholderia cenocepacia CR318, a Phosphate-Solubilizing Bacterium Isolated from Corn Root

2017 ◽  
Vol 5 (23) ◽  
Author(s):  
Filip Zekic ◽  
Brian Weselowski ◽  
Ze-Chun Yuan
Keyword(s):  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Phosphate Solubilization ◽  
Burkholderia Cenocepacia ◽  
Ecological Sustainability ◽  
Content Type ◽  
Phosphate Solubilizing ◽  
Circular Chromosomes ◽  
Insight Into

ABSTRACT Here, we report the complete genome sequence of the phosphate-solubilizing bacterium Burkholderia cenocepacia CR318, consisting of three circular chromosomes of 3,511,146 bp, 3,097,552 bp, and 1,056,069 bp. The data presented will facilitate further insight into the mechanisms of phosphate solubilization and its application for agricultural and ecological sustainability.

scholarly journals Variation in Cell Surface Hydrophobicity among Cryptococcus neoformans Strains Influences Interactions with Amoebas

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Raghav Vij ◽  
Carina Danchik ◽  
Conor Crawford ◽  
Quigly Dragotakes ◽  
Arturo Casadevall
Keyword(s):  
Cell Surface ◽  
Cryptococcus Neoformans ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Natural Soil ◽  
Order Structure ◽  
Hydroxyl Groups ◽  
Biophysical Properties ◽  
Content Type ◽  
Biophysical Parameter

ABSTRACT Cryptococcus neoformans and Cryptococcus gattii are pathogenic fungi that cause significant morbidity and mortality. Cell surface hydrophobicity (CSH) is a biophysical parameter that influences the adhesion of fungal cells or spores to biotic and abiotic surfaces. C. neoformans is encased by polysaccharide capsule that is highly hydrophilic and is a critical determinant of virulence. In this study, we report large differences in the CSH of some C. neoformans and C. gattii strains. The capsular polysaccharides of C. neoformans strains differ in repeating motifs and therefore vary in the number of hydroxyl groups, which, along with higher-order structure of the capsule, may contribute to the variation in hydrophobicity that we observed. We found that cell wall composition, in the context of chitin-chitosan content, does not influence CSH. For C. neoformans, CSH correlated with phagocytosis by natural soil predator Acanthamoeba castellanii. Furthermore, capsular binding of the protective antibody (18B7), but not the nonprotective antibody (13F1), altered the CSH of C. neoformans strains. Variability in CSH could be an important characteristic in comparing the biological properties of cryptococcal strains. IMPORTANCE The interaction of a microbial cell with its environment is influenced by the biophysical properties of a cell. The affinity of the cell surface for water, defined by the cell surface hydrophobicity (CSH), is a biophysical parameter that varies among different strains of Cryptococcus neoformans. The CSH influences the phagocytosis of the yeast by its natural predator in the soil, the amoeba. Studying variation in biophysical properties like CSH gives us insight into the dynamic host-predator interaction and host-pathogen interaction in a damage-response framework.

US energy high-yield bonds spur default risk

2015 ◽  
Keyword(s):  
Interest Rates ◽  
Default Risk ◽  
Oil Price ◽  
High Yield ◽  
Content Type ◽  
The Past ◽  
The Us ◽  
Low Interest Rates ◽  
Investment Grade ◽  
Energy Companies

Subject Impact of the oil price drop on energy high-yield bonds. Significance The over 50% oil price drop since June 2014 is hitting bonds issued by energy companies, particularly those issued by sub-investment grade corporates. The US high-yield bond market has been growing rapidly over the past five years. The shale boom has generated considerable investment, mainly funded through the issuance of these bonds which benefit from historically low interest rates. As the oil price has plunged, the spread over Treasury yields paid by the average issuer in the energy subsector has more than doubled between July and the December 2014 peak. Impacts Yields currently offered by the energy subsector are not far from pricing in a default scenario. Persistently low oil prices will further darken the outlook for the energy subsector and the high-yield market generally. A possible default cycle in the energy sector could accelerate outflows, overstretching the sector further.

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